No, it's not selfish *not* to break up a relationship because of an infatuation. That's the opposite of selfish. What you should do is to stop seeing and talking to this other guy except in group situations and start thinking about what the possibility of that relationship offers you that your current one doesn't and figure out how to get that back in your current relationship, whether that means spending more time together just the two of you or what. Treat it like you secretly cheated, even though you didn't. If you and your boyfriend are really still in love, you'll be able to rekindle your relationship, and if not, at least you'll have learned *that*. And maybe be able to move on with any number of people without breaking up another couple and losing a friendship.