Take with this what you will, and remember no two couples are the same.
It has nothing to do with confidence, and everything to do with facing self esteem and insecurities. So as HARD as this sounds, you just have to not care. I know that sounds kinda shitty lol. So listen, your partner is with you for a reason, and a damn good one at that! You have to understand, there will be times when he looks another girl up and down, there will be times maybe he even makes commentary you do not like, BUT you have to remember… You are just as in control of this relationship as your partner. Healthily, what works for one relationship might not work for the next. But relationships EASILY die when there’s no sense of self security. That’s what crashed my last relationship ( very recently too ) , he was SO insecure in the last few months, it truly started to give me the fucking ICK just hearing him breathe. Everything I did was followed by comments, questions, and his insecurities that eventually turned me all the way off for good! That part of you has to let go. Be yourself without making yourself dependent on his affinity for you. You are your own person, as is he.
Best of luck on whatever advice you take / don’t take!
P.S know this sounds harsh. TRUST ME I KNOW. But it’s better to learn it, than try and figure it out strategically, later to only be hurt.