I had a similar problem with the first person shooter Unreal Tournament. The game is great fun as a single player against robots (Bots), but this game includes the interface which puts you up against other live players world-wide. I was hooked, sleep was minimal.
To make matters worse, UT ships with a Level Editor, which lets every user create and design the playfields (maps). You get to carve rooms, texture walls, create ambient sound triggers & colored lights, place items, weapons, player pathnodes ... making an infinite number of possible places to play. I was addicted. The wife was not pleased with this.
However she understood this as a creative outlet, the building of the levels as opposed to mindlessly playing the game, and she eventually offered suggestions like, "That room is too dark," or "those textures don't work." She would never actually sit down and play, and sounds like your wife isn't into the game you're playing.
As my priorities shifted from late-night gaming to late-night bottle feeding, I not only stopped making maps, I quit playing the game altogether. Sounds like you have two options:
1) Ignore the problem, hope she doesn't up and leave (this would not be an option in my mind)
2) Sit down with her, explain this is something you truly enjoy, and work out a schedule you're both happy with.
I'm fully aware how you can wrap your head around one single thing for months, how hard it is to think of anything else. Make sure you put your wife, or any other person in your life, before anything as simple and unimportant as a video game.
Good Luck

T