Decisions....

Does he have a reason not to trust you?
If not, insecurity like this is a sign that he has trust issues and will show up in other ways...
But, I have little patience for jealousy, I think it means that I am being objectified and tends to make me paranoid about the reasoning behind it. Why don't they trust me, does it mean they are not trustworthy and are projecting?
There is a core issue that I do not know and they will rarely share it.
I have little tolerance for it and have, in the past, always ended relationships with jealous people.
Perhaps I am not the best person to discuss this with.

What does flirty mean? Seriously, is it just smiling and being "flighty" and fun with men or physical and lots of dreamy eye contact while letting men buy you drinks and slow-dances while never telling them you are married/engaged/in a relationship?
Blaming you for their behavior is very telling and makes me think the former and not the latter, but you will have to tell us.