Silent,

No, you're not doing anything wrong by having other friends. Not having other friends is the fastest way to breaking up, in my opinion - no one, and I mean no one can spend ALL their time in someone else's company to the exclusion of all others and not begin to hate the situation and resent the person fairly quickly. Outside interests and friends are how we retain who we are as individuals within a couple, and not some amorphous dual person.

However, in her defense, what are these friends of yours like? Do they go out of their way to make her feel welcome in their presence? Do they treat her kindly? Do they act like she's her own person and not some extension of you? What do you guys do when you're together? Is it something that she might want to do as well, or is it something she's totally not interested in?

She may feel alienated by your friends and may not want to spend time with them - however, it is very very hard to tell your significant other that you really can't stand their best friends - which may be why she doesn't really want to discuss the situation.

Consider this from all angles, and then I think your gut will tell you to stay and make new friends that she's comfy with or run like hell cause she's controlling.

Keep us posted!

some of it's magic
some of it's tragic
but i had a good life all the way......
~jimmy buffett