My wife is a very independent cuss, to say the least. After nearly 20 years, of which 7 or more we were living together, brought our first home, she finally relented to say "I do". Which was purely a financial reason behind it, for my health insurance.
There were conditions attached. Since she came from a family were mom and dad were seemingly constantly at war and both feeling trapped, condition #1 was if a time ever came the other wanted out, we part amicably. Yes, it will hurt but far better then growing to hate eachother. Condition #2 was sort of related to #1. Her mom, basically was also a slut. She slept around a lot with all the usually silly reasons why home late from work. Which sure did not fly well all around. Especially if there were 2 to 3 young children waiting for some adult to make it home. Except the only adult in the house was her and she was seven. So, condition 2 basically was an open marriage. If it ever happened the other needed a 'fling' you can with certain guidelines such as being open about it and not 'bringing any little friends home', as in STDs.
It has been 15 years since she said yes, neither has come to pass. But it is now Condition 2's turn to become a lot more real. Part of her reaction to my coming out to her is still the same as it was 5 years ago, "I like men and what they have and can do. I didn't marry a woman". We have had talks about "Options" for the future since she cannot imagine wanting to spend the rest of her life with anyone else but me. Nor can she imagine ever wanting to go through the effort to accomplish that with anyone else. (Re independent cuss).
Yes, I know at the very least I'll feel weird if it comes to be. Perhaps worse since I lived through wife #1 sleeping with a guy before our separation. I also know very very well she did sign up for this. In fact she had my honest assurances this was out of my system after 2 much earlier experiments.
We grow, we change, life is not stagnant. If you cannot adapt to changing conditions you die. Be it changing conditions on your job, neighborhood, or marriages.