Bf (24M) doesn't believe in opposite sex friends, I (22F) do. Help.

Having opposite gender friends

I (22F) believe it's okay to have opposite gender friends, as an adult i think thats part of becoming secure with yourself and in relationship. I think its healthy to have friendships with the opposite sex, my boyfriend (24M) does not agree.

I strongly believe he's too insecure to come around to my mindset. We are both in individual therapy, as well as couples therapy.

Yet hes still so insecure with himself. If i bring up a male coworker he says things like "I dont trust him" or "that's weird, they're flirting with you" when that's not the case. He has told me " i know men" and everyone is just trying to fuck. I disagree entirely. My coworkers are married older people, 100% just platonic work friends. We dont talk outside of work so i wouldn't even say they are real friends.

Has anyone had success in their partner changing their mindset?

If he doesnt change, im not sure this relationship will continue. Im really hoping to hear that as you get older you get wiser and more secure with yourself.

Also opinions on the subject would be appreciated, as i cant see this from his perspective.