The "funny" part (this is the humor section) is the courts don't care about marital fidelity. Someone can cheat and still get 1/2 of the marital assets.
However, if you keep good records, they only get 1/2 of any increase in assets.
My ex-wife was unfaithful, and she got 1/2. But only 1/2 of what was added to my 401(k) the cars, home, etc since we married. Everything I had before the marriage automatically came off the table during the division of assets.
Now isn't that funny?