I simply view all relationships as a series of agreed rules between two consenting adults. That's it. Every relationship is just a series of implied or explicit rules. There are some people with whom I have sex and some people with whom I don't. That sex can be fun like a shared hobby or it can be caring because there are feelings involved. That is to be worked out between me and the other person (or people). I don't care about fidelity, I care about honesty.
To my mind, Marriage (and to a lesser extent monogamy) is an oppressive form of ownership couched in terms of ownership and is profoundly anti-women- as I'm about to get into with the lovely Ben Sledge.
You're welcome to come join the bun fight when it begins... https://medium.com/p/cb6597e4edd9