Maura has a really good point, than when they do come home from your wedding they still will be in the same situation as now. I think 2 mos from now, is too long for them to wait to talk. If i had to hold something in for two months it would eat at me. She should just ask him why he was in his office till 4 am. She should try to talk to him, calmly.
I'm sure the alone time at your wedding would be great for them, but if they are having problems now she should try to talk to him now. Waiting could make it worse. More tension could build. I hope everything works out for them.