I personally found some great weight loss tips on this forum and I'm sure that by browsing through them you'll find some help. As for late night snacking, it's definitely a problem. When I was in college I was living with my best friend, she also had a job that kept her at the office until late at night and she would arrive home really hungry. I would occasionally join her for dinner even though I had eaten just a couple of hours before. Especially with couples, it's hard to eat separately because we tend to bond over food. Maybe you could try eating something else than what your wife is having and cook separately. This way you could still enjoy dinner together but without having too many calories. Also, I know weight gain comes from consuming more than you burn, so how about exercising before you go to sleep?
I know I tend to snack while I watch TV in the evening, but try and replace your snacks with healthier choices: walnuts, pumpkin seeds, dehydrated fruits. I don't know if this is helpful but I wish you good luck!