Yeah, I'm wondering about helphubby's W's reaction to that. I've pulled a similar kind of thing in the past with my W and what I got was, "You are being manipulative." And you know what, she was right. I might have been saying it because, on the surface, I didn't want any more conflict, and I was trying to be generous and loving, but, deep down, I really wanted a reaction from her.
That doesn't mean it is somehow evil to make such a resolution. I think it's a way we (HD men) try to "stir the pot". In other words, it's an indirect way to get a discussion going about the subject of why our marriage is sex-starved.
As for Shirt, your instincts about an affair might or might not be grounded. The staying out until 3am would bother the heck out of me. Maybe investigate further?