I probably wouldn't go as far as dumping your gf, but I'd certainly sit down with her and discuss why you play "so much" poker (maybe 5 face-to-face games a week? Or a couple of hours a day?). Perhaps if you describe it as a hobby and demonstrate that you're not actually losing any money on it, she might accept it.

IF she doesn't, then you've got (repeat "got") to think about what YOU want. Which is more important - your life as present without poker, or the fun of being single (playing as much as you want to) and chasing after skirts...

I hate to say this (having come from 2 LONG relationships during Uni myself) but being single and having the freedom to do whatever you want to does have a great deal of benefits. And you can always masterbate.