I strongly suspect that that last may well be tempered by how much the crusher in question likes/respects the crushee's choice, tbh. Social narratives to the contrary, we eventually learn the hard lesson that we can't be everything to the people we love; presumably anyone who genuinely cared passionately for their friends' well-being would be happy for them, assuming they'd found a person who cared for the crushee as well as they would. (Or maybe not! Feelings are complicated.)