No such thing as males and females being just friends.
One always wants more. Attraction gets in the way, that's why u made friends in the first place, attraction, not only physical either.
An honest man will tell u straight out, he doesn't make friends with women just for friends.
Especially when your in a relationship, I know I'd hate it if my partner had male friends that asked her out for coffee etc, alone or one on one, they want her. It's simple.
If u want my advice bro, tell her how u feel, if she doesn't agree, move on altogether, it will just head fck you