This is why monogamy is stupid. You should be happy for your wife, that she gets away from the stress and rigors of the daily grind for a week. And if that week includes getting banged like a screen door by a young local in a way you couldn't possibly achieve at your age, even if you did lines of viagra off of a strippers bum, then so be it. She only lives once. She should get to be physically fufilled in a way you can't provide at your age. Likewise, you should be able to fondle breasts that aren't saggy and grab a firm buttock etc etc.
But no, we've taught ourselves that we're each other's possesion and we must deny harmless happiness for the sake of outdated cultural mores.
Be a man of the new millenium. Hand her a box of rubbers on the way out the door and tell her to have the time of her life.