Hi Flossy73,
Maybe if you went out with an older guy you wouldn’t have this feeling. Guys DO like to go for younger women (if they can get them.) So perhaps you’re picking up on that. Let me put it this way. A fifty year old guy would be lucky to have you if you’re forty, and he couldn’t even think of getting with a twenty year old. If you and your guy are forty, well, it has happened that a youthful forty year old could get a twenty something year old.
Of course I’m being outrageously un-PC and general. Your particular guy is a unique individual. You should feel secure. But you don’t because you can’t see what’s in his mind and heart, you can only go by intuition, actions and what he tells you.
What I would do is be the best looking and/or happiest woman of my age I can be. Don’t go overboard, but any thing that gives you a bit of confidence can help. A spritz of perfume. A new shade of lipstick. A hip new shirt. Anything that give you joy in and of itself. Then when an attractive middle aged guy looks at you your BF will be reminded of how good he’s got it!
Best,
Inky