My girlfriend and I have an arrangement, and it all works out quite well. I only rarely hear gentle sobbing from the kitchen over the sounds of zombies being mangled and turning up the volume solves that problem.
But seriously, my other half tends to be pretty accepting of my inability to prise myself away from a game I'm really into. A few times she's even made an effort to play it too, which is nice in an "Aw, bless her poor lonely neglected heart" kinda way. In exchange for her understanding and patience I make an effort to ensure I don't put gaming ahead of anything significant, such as plans for an evening out or lunch with our respective parents, etc.