how do I make my bf more confident

my bf is really insecure & idk why. he’s the most attractive guy I know all my exes were the stereotypical “cool” guy and he is so far from that. he only is 100% himself around me but if I start arguing with him he’ll get all awkward again and apologize excessively. I’m his first serious relationship & I’ve never dated someone like him before so idk what to do. he’s shy and kind of awkward and kind of a “loner”. I just wish I could bring out his confident side. any advice on how to get my man to come out of his shell in public?