Don't you think that (going on the date) would come across as needy and clingy?
I might have missed some things from previous, but under these conditions I don't think it would appear needy and clingy: 1) This was already arranged so it's expected (despite her remorsefulness of last night) 2) He can tone down these emotions and eliminate all expectations. It has to be, "what the hay, I have nothing better going on" type attitude 3) There isn't going to be talking about the relationship or talking about forgiveness. You can't forgive what you don't know about. 4) It's short, sweet, and is basically hanging out in a relaxed manner. 5) If this isn't a date that was already set, or if he's unable to do exactly what's written above, then I agree...needy and clingy and desperate for his wife.
That being said, if handled right (ie he either just doesn't bring up this "date" or he begs out with "something has come up") then not doing the date is fine too. What I don't like as much though is that it's natural to beg out in this situation. His wife would see it as a sign that he's crushed or too angry to do this. I just like it when you get the opportunity to show that you could care less what your spouse is doing, that you are in control of yourself. Know what I mean?
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer