Your wife's hand-holding, etc., was very likely for show in front of her parents. She doesn't want them thinking poorly of her, and this is very common. I would measure her reactions toward you when others AREN'T around to see them, and go by that.
As for the sex, you've been tagged. It's either her wanting to see if she can still use sex to exert control over you, or she's wanting to "test" it, to see if she still has "those" feelings for you when ML, to compare them.
It's really not any more complicated than that; both things are very much "script" in these situations.
