I still play and am 25. I have a wife who understands, one kid and one on the way, and a 60 hour+ week job. Many people have hobbies. I feel as long as I dedicate time to other things, a few hours a week to unwind (instead of watching TV, etc) is okay.
The only real difference is now I limit what games I play. Before I would buy and try everything. Now, I realize I simply won't have enough time to beat Oblivion, NFS:MS, GRAW, HL2, etc. So, I pick and choose more.
I still play BF2 on a weekly basis with one of my friends. My wife (who likes the occasional game of SSX or puzzle game from Xbox Live Arcade, but is by no means a gamer) even allowed me to purchase and upgrade 3 gaming computers (one for me, two for my guests.) One of my Christmas presents last year was a 7800GT.
Dump the girlfriend for bashing your hobby. Video games are a multibillion dollar market and are rivaling even Hollywood. It is an accepted form of entertainment and even builds bonds between friends.