I've read a lot of the posts on this web site and I've yet to find anyone suggesting that it's okay to betray a commitment between a husband and wife.
The term adultery has evolved to mean any sexual interaction between two people who aren't married. For some reason we always assume that adultery is restricted to sexual interaction. The root meaning of the word is "to corrupt".
We suppose that the most common causes for betrayal in marriage is sexual attraction but from what I can tell that's like putting the cart before the horse.
The corruption is the act of betrayal.
I know of many instances of corrupt relationships between people who strictly practice monogamy and practice a type of betrayal that far surpasses sexual unfaithfulness.
Iíve come to believe that if I canít be honest with my wife about my sexual desires I canít be honest with her about anything, really.
I think open marriage and polyamory is a sincere attempt to not betray someone we love.
Jesus condemned immorality or illegal sexual activity. Again I haven't read anything here that promotes illegal sexual activity.
The last I knew two people living together isn't illegal.