You don't give enough details for us to give good advice.

My best friend of 20 years is Male and I am Female. Our spouses are fine with our friendship becuase we have great boundries. As on, we aren't overly affectionate, we don't talk about our relationships with eachother in too much detail because you can't really do that when you have an opposite sex friendship. I would absolutely understand if my husband got upset if I was talking about my sex life with my bestie for example.

8 have noticed many other people in a friendship where people are the opposite sex don't set firm boundries, and are always surprised why the people they date get upset. Things like sitting in each other's laps and cuddling. Doesn't matter if you have been friends forever, it's inappropriate to do when your in a relationship.

You haven't given us enough info to know if you and your friend have a healthy friendship, or if you guys are doing things that would make most significant others uncomfortable.

My bestie and I use to have dinner together once a week or every other week when we lived near eachother. We took turns paying for eachother. Our spouses, who were just our boyfriend/girlfriends at the time were fine with it.

If you guys don't do any of the crap I said above, and you spend more time with your gf than your friend, the. Your gf is just insecure.