You don't really understand it yourself -- but there is just something about watching your wife prepare for a date with another man that makes you feel -- jealous and rejected certainly, but also incredibly excited.
You're not sure what to say. You want your wife to do whatever SHE really wants to do, but the idea of her spending an evening with her ex makes you really nervous about what might happen. Your wife has mentioned a couple of times -- at moments of frustration because of your poor performance in the bedroom -- how great the sex always was with him. You're pretty sure, in fact, that she has already decided that, no matter what you say, that she will be having dinner -- and probably a lot more -- with him this weekend. Indeed, when you do say to her that it's up to her, she just says that it's such a sweet gesture by him that she can't really say no -- and then she rushes off to text him to tell him how much she loves the cake and that she would love to meet him on Friday.