OK, it's a trust issue, but it is also a common sense issue, and something doesn't make sense here: If they "had a crush on each other," why didn't they act on it? Perhaps LW's boyfriend and best friend are completely trustworthy. In fact, maybe their relationship with LW is WHY they're complete trustworthy. They may be the two most virtuous people in the world, but I'd be bothered by the possibility that they might have feelings for each other even if I could count on them not to act on them! I'm not talking about irrational jealousy here - I am good friends with a few of my husband's ex-girlfriends, and I've never had a moment's worry about any of them. But I sure wouldn't want to be married to him if I thought he had major unresolved romantic business with any of them - even if he were completely faithful.