Is your dude always talking about himself? Or does he humblebrag about his former sexual conquests, like he doesn't have a clue how that might make you feel? Stuff like this can sometimes be innocent - naive, perhaps - but these behaviors could also be relationship red flags. If you're dating a guy and you're trying to figure out how to know he is the one, watch out for the dating red flags below. They might just mean you're dude's gonna turn out a dud after you two settle into a relationship together.