I don't bring my girlfriend around my friends as much as I probably should, is that bad?

First off, she’s met my inner circle of friends once and that was when she brought her friends along as well. We all had a great time and haven’t really hung out since. I’ve been with my girlfriend for a year and half already and we’re going to college together in Waco. This is mostly due to the summer before senior year because I fucked up and had to fix our relationship. We just stuck to each other like glue since the summer and all senior year I’ve been with her or, occasionally, her friends as well. I don’t know why I’m like that, its just the way it is. When I asked her about it, she said it USED to bother when I didn’t bring her around my friends as much, but now shes used to it. That kills me inside, but its just…different with my friends. I honestly haven’t hung out with them in forever because I’ve just seemed to..outgrow them in a way. I mean sure, they’re still my boys and we’ve hung out a few times during senior year, but I’ve been with my girlfriend much more. She goes to school across town so I’m always in that area and never near my friends. Prom is coming up and I know my girlfriend is a bit nervous since she hasn’t been around my friends much. Am I wrong for this or is it justified? Help!!!!