I can also related to your initial comments because I've had bad experiences , the way everyone acts out there in the world is all down to personal experience. My advice to your boyfriend next time op is firstly not to listen to your fashion advice haha ! if you're going to a wedding function wear a suit . It will also make him feel a hundred times more confident trust me , I feel like a god in a fitted suit . Secondly is to mingle , with everyone . If that guy that smiled and tried to hug your wife is also smiling and laughing at your small talk and banter then you're probably not going to feel threatened. If you're avoiding a situation then that sends signals , you have a boyfriend but he's waiting in the car ? Why is that ? Relationship not doing so well? Also sends signals to your girlfriend. Be present !