Not saying it is not fun, just saying it gets boring quickly. Especially if it is always with the same person. Why do you think people cheat each other? They do it even when they love each other on a personal level.
It is just our instincts. We are two legged dogs. We want to fuck everything that moves.
Simple solution: Negotiate an open relationship. Then you can fuck all sorts of people and you don't have to go to Barcelona because your wife does. She can go with a boyfriend and you can do the Colorado mountains with your woman.
All works out.