I think I smell another get together happening this weekend, and if it turns into an overnighter, I guess I will have to up the stakes a bit, and ask her to leave the house.
How many kids do you have? Are they a lot of work?
Why not NOT be available this weekend yourself so your wife has responsabilities and can't just fly off to some romantic escape?
I don't have enough details to know if this advice makes sense.. weigh accordingly...