I wonder if you are hanging out with the wrong set of people? For the most part, my boyfriend and I keep up separate friends because we are both interested in things that the other one is not. I like plays, he likes motorcycles. I go out without him all the time and don't find that people hassle me over it.

I would start with trying to be okay that you have separate friends. Doing women focused stuff might help too -- stuff where it is expected that you won't turn up with a mate.