Big problem with my girl(s)

I've got a big problem.
I have a really sweet, nice, good girlfriend for allmost a year.
I love her. That's not the problem.
The problem is I know a girl, I like very much too.
She's totally different different to my girlfriend.
A long time, I thought she'd be a level too high for me, but the last days, I realised she isn't. We do many things together with friends, at school, so on...
She likes to do things with me.
I'm happy to be next to her, but I'm also really happy to be next to my girlfriend.
I don't know, if there'd be more between us, if I'd try.
I don't want to destroy the friedship or the love. But when I'm next to my gf I sometimes think of her and the other way round.

I don't know what to do now, I'm really despaired.

>>10
Exactly as I said. "I like this girl, we have no serious problems, but the other one might be better." Ask yourself, IS the other girl better or not? If you don't know, don't risk it. Unless you are unsatisfied with the current relationship. In which case, bring it up with her. If she's mature at all she can talk about it and then you both can decide what to do. Of course it'll be difficult, but working it out will save you fuss now and in the long run.

Seriously, my health sucks as well. The girl I'm closest to claims to love me, is willing to wait out my problems and help me if need be, but I still know that at any time she can do as she pleases and stay with another guy. It's her choice, and we can and already do talk about her choices. This sounds like very much the same situation.