My marriage ended because of it and I have been with quite a few jealous men who don't like me having male friends.
I think jealousy is very destructive, and whilst I know it's a natural human emotion to have about someone you fear losing, I have learned to keep mine in check over the years because.......at the end of the day you have to let people do what they want.
Would you have a problem with your husband / dp meeting up with an ex girlfriend for a coffee? I have met people who say if you're in a relationship you should entirely cease contact with anyone you've ever slept with. I think this is really silly. But am I in the minority?