It sounds like you've gotten into an unhealthy habit there. Speaking as a guy who have tried a lifestyle similar to this, it will damage not only your own health but your relations to other people. From what you write in your post, your girlfriend is genuinely worried about you. The least you should do is put down the controller, switch off the tv and talk about it. If you think she is being unreasonable, ask why she feels that way. Maybe you discover that your girlfriend will be understanding and accept you spending a few hours playing each night, as long as you spend some time with her too. Just a friendly tip: people around you notice changes in your behavior. Much more so than you do yourself. And when you play a videogame day and night, every free hour of your day, you eventually change a lot. So if people around you start to sound worried about you, it's time to take a critical look at yourself and the choices you make.