Feelings for Your Partner's Best Friend (or Sibling)?
Entry No. 084 ·
By The IF Team
Having feelings for your partner’s best friend — or for their brother or sister — is more common than it feels from the inside, and on its own it is not cheating. A feeling is not an act, and it is nothing to be ashamed of. What matters is what you do next, and you have real options: hold it quietly, turn the volume down without pulling away from your partner’s world, tell them how you feel, or say it in a sealed message that waits until you are both single. The same holds whether it is your boyfriend’s best friend, your girlfriend’s best mate or your husband’s brother.
The only lines are cheating and lying, and both hurt people. Everything here sits on the honest side of them, and so does IF, the dating app we built for feelings like this: no conversation can open on IF while either of you is in a relationship, but you can still say what you feel.
It rarely arrives with any drama. He is the one who asks how your mum’s operation went when your partner forgot. She sends you the voice note nobody else would find funny. You have heard every story about your partner at nineteen from the person who was actually there, and somewhere along the way the person who knows your partner best started to feel like someone who knows you. You are not broken, and you are not alone.
This guide is for the reader who is in the relationship. If it is the other way round, and you are single with feelings for your best friend’s partner, read our guide to having feelings for your best friend’s boyfriend or girlfriend. For the wider picture, start with having a crush while you are in a relationship.
Why it happens inside their circle
Attraction feeds on proximity and familiarity, and your partner’s inner circle supplies both. You see them often, you are encouraged to like them, and you trust them by proxy because the person you love already does. They also arrive without the ordinary friction of a shared life: you have never argued with them about the bins or whose turn it is to ring the landlord.
None of that means something is wrong with you or your relationship. A study of adults in exclusive relationships found that crushes on someone other than a partner are common. Unlike most crushes, this one cannot settle at a distance: it sits at the birthday dinners, in the group chat and, if it is family, at every Christmas for years to come. Two bonds are in play — yours with your partner, and your partner’s with someone they love — and you would rather lose neither.
Is it cheating to have feelings for your partner’s best friend?
No. Noticing someone is not a betrayal. When researchers asked people where they draw the line, sexual contact was the clearest case of infidelity, while emotional and online behaviour counted as infidelity to a lesser extent. The line sits in what you do with the feeling: a crush stays honest while it stays in the open, and stops being honest when it turns into things you would need to hide:
- Messaging them privately in a way you would not want your partner to scroll through.
- Engineering time alone: the lift home, the last drink after everyone else has left.
- Confiding in them about problems in your relationship in a way that pulls you closer and your partner further out.
- Flirting “just to see” whether they flirt back.
- Lying, to your partner or to yourself, about any of the above.
If you recognise yourself in one of those, it is no reason for shame, just a signal to bring the feeling back into the open. Our guide to emotional affairs looks more closely at where the line is.
Turn the volume down, not the lights off
You cannot vanish from your partner’s best friend or sibling without your partner noticing and asking why. The aim is to take the private charge out of the closeness, not to remove the person.
- Quiet the one-to-one channel. Keep most messages in the group chat, let your partner make the plans, and mute their stories for a season.
- Keep showing up, in company. Stay friendly and a little dull, and leave when your partner does.
- Mind the confidant role. Complaints about your partner belong with your partner first.
- Tell someone. Feelings kept entirely secret tend to grow in the dark. Say it out loud to someone you trust, or write it down.
- Ask what the feeling is pointing at: them, or being listened to, laughed with and noticed? Some of that may belong in your own relationship. Some of it may simply be them, and that is honest too.
Girlfriend, boyfriend, husband or wife: what changes
Your boyfriend’s or girlfriend’s best friend
With your boyfriend’s best friend, you are probably up against a friendship older than your relationship: the mate he grew up with, the flatmate from university. A best friend who senses something may go quiet around you or mention it to your boyfriend, so if he is going to hear about it, let it come from you, honestly and on your terms. Keep most of your contact inside the group, and let your boyfriend be the bridge between you.
If you are attracted to your girlfriend’s best friend, remember that a best friend is usually the person your partner tells everything, including things about you. Whatever you say travels. Some attraction passes on its own; if this does not, an IF lets you say it without building anything around it. And if you are dating but not yet committed, you have an honest exit: if you would rather be single, say so and end it cleanly, before anything begins with anyone else.
Your husband’s or wife’s best friend
A spouse’s best friend usually predates you: the best man, the godparent, the voice on the other end of the phone every Sunday. A crush on your husband’s or wife’s best friend can also be tangled up with what married life has settled into: the tiredness, the sense that nobody asks about your day any more. If it will not fade, it deserves an honest conversation about your marriage. And if you still want it said, an IF keeps it sealed: no conversation can start while either of you is in a relationship, and nothing opens unless you are both single one day. If that day ever comes, you are already there.
If it is your partner’s sibling
A crush on your husband’s brother, your wife’s sister or your partner’s sibling sits inside a family, and family is permanent. You will share holidays for decades, and your partner will never stop being their sibling. That makes structure more useful than distance: see them at family occasions rather than alone, and never become the in-law who takes their side against your partner. If the feeling lasts and you want it said, an IF holds it sealed: it never says who sent it or what it says unless you are both single one day.
A note on the words. “Attracted to my brother-in-law” can mean your spouse’s brother, which is what this section is about, or your sister’s husband. If it is your sibling’s partner, read our guide to a crush on your sibling’s partner.
When your partner’s best friend flirts with you
Sometimes the question is theirs as well as yours. If your partner’s best friend flirts with you, it can be flattering and confusing at once, and it does not make either of you a bad person. People flirt out of habit, nerves, affection or a feeling they have not worked out yet.
What you can decide is your reply. Flirting back in private is how a feeling turns into something you would need to hide, so keep it warm and in the open: answer the question rather than the subtext, and bring other people in. If it carries on and you would rather it did not, say so kindly: “I’d rather keep things easy between us.” If it still carries on after you have asked, your partner deserves to know, told plainly and without drama.
If it does feel mutual, the order matters more than the feeling. A study of relationships formed through mate poaching found that people who had been lured away from a previous partner were less committed and less satisfied in the new relationship. A relationship that only begins once you are both single starts in the right order, and that is the order an IF keeps: either of you can say it now, and nothing opens until you are both single.
Should you tell them how you feel?
You can, and it takes courage; some people would rather know. But be clear-eyed about the risks of saying it face to face. Here it lands on two relationships at once: yours, and your partner’s bond with someone they love. It puts the person you tell on the spot, and it cannot be unsaid the next time you are all in the same room.
There is a middle path between silence and a confession. You may be better off sending a sealed IF: it says it without asking anything of anyone today, and if the timing ever lines up, you are there to show them how much you have always liked them.
Should you tell your partner?
A feeling for someone else is nothing you have to hide from your partner. A passing crush on a stranger may never need saying; one about someone your partner sees every week is different, especially if it has changed how you behave. If you tell them, make it about the two of you — what you noticed, what you are doing about it, what you want more of together — rather than a confession that puts their friend on trial. And if you have sent an IF, that need not be a secret either: it is sealed, not hidden, and having IF on your phone is not cheating. Our guide to telling your partner about a crush covers when and how.
If the feeling lasts, look at your own relationship
A study that followed people with crushes for a year found that most crushes did not harm the relationship; the ones linked to falling satisfaction were strong, lasting crushes, and crushes in relationships that were already unhappy. If that sounds like yours, take an honest look at your relationship: work on it together, or end it cleanly. If you leave, let it be for what is true between the two of you, and let the feeling for someone else wait its turn — an IF can hold it, sealed, until you are both single. Our piece on whether to break up because you like someone else can help you tell the two apart.
If the thoughts have become constant, talk to someone; you do not have to carry it alone.
Where IF fits
IF is the dating app for everyone, single or in a relationship, built around one idea: you should be able to say how you feel, whatever the timing. While either of you is marked as in a relationship, no Like, match or chat is possible, so nothing can start between you and your partner’s best friend or sibling on IF. What you can send is an IF: a private, sealed message of up to 250 characters that opens only once you are both single.
That makes it a release valve for exactly this situation. The feeling gets said, in your own words, and can stop circling your head. Your relationship, their friendship and the family dinners can all carry on, because a sealed IF asks no one to decide anything now. Nothing about it needs hiding, and an IF can be sent honestly whatever you feel about your relationship.
If they are single, your IF reveals when you change your own status to single; if they are in a relationship too, it opens only once you both are. When it is revealed, they see your profile and your message and choose whether to accept, and accepting opens a chat with your IF as its first message. How an IF works covers every combination.
In a circle this close, know how it lands. If they are on IF, they will usually be told an IF is waiting — never who sent it or what it says — though people who know each other well can guess from context. If they are not on IF yet, one sent to an email address they gave you triggers one short invitation email, without your name or words; one sent to a phone number or Instagram handle simply waits in case they join. Knowing that, the choice is yours.
Your first IF is free. Writing one takes a little emotional bravery, and that is the point: you say exactly what you mean, and then it does the waiting while you get on with things. If it ever opens, maybe it leads you where you were meant to be all along.
Questions people ask
Is it normal to have feelings for your boyfriend’s best friend?
Yes. Proximity, familiarity and borrowed trust are the conditions attraction grows in, and the person closest to your partner supplies all three. On its own it says little about your relationship, and nothing bad about you.
How do I stop having feelings for my boyfriend’s best friend?
You probably cannot switch it off, and you have nothing to be ashamed of. Give it less to feed on: quiet the one-to-one channel, see them mostly in company and put more attention into your own life. Writing it in an IF can be what finally lets it rest, because it has been said. If it does not soften with time, talking to someone can help.
How do I know if my boyfriend’s best friend likes me?
Often you cannot know for sure, and reading every glance keeps the feeling loud rather than answering it. The usual signs: they seek you out in a group, remember small things you said and message when nobody else is around. If it feels mutual, keep it in the open; a sealed IF lets you say so now, and leaves the rest to timing.
Is it wrong to have a crush on my husband’s brother?
No. The feeling is not wrong; cheating on your husband, or lying to him, would be. Keep contact to family occasions, and if it persists, look honestly at your marriage. If you need it said, write it in an IF: no conversation can open while either of you is in a relationship, and nothing is revealed unless you are both single one day.
If we break up, can I date my ex’s best friend?
Adults can, in time, though your ex may lose a best friend as well as a partner. End things honestly first, and give everyone real time. If you sent an IF while you were together and they are single, it reveals when you change your status to single: proof you felt it all along and said it honestly. Then they choose whether to accept.
Right person, wrong time? Wait for them on IF: say it once, in a sealed message, and keep living your life until the day your timing lines up.