Uh, hello, Mickey. You left your wife for another woman, came back a year later, and yet still want the girlfriend, not to mention your wife recently lost her job, and you think your wife has no reason to be depressed? That she's just lazy? If you don't think that she knows you want someone else, you're fooling yourself. And do you talk to her the way you talk about her here? If you do, then it's no wonder she's unhappy. Maybe the problem is your attitude towards your wife.

Get marital counseling. It's the best thing you could do for both of you. You left your family for a year, and you don't think that might have done some damage to your relationship? Of course there'd be a hole. Of course there'd be something missing. And maybe your wife seemed okay at first, but depression doesn't just appear for people. It can be a long and slow decent.