Consider if you get married or have children.
Marriage and children give people a reason to stay in a relationship that they might otherwise abandon. If there were no barriers to terminating and beginning new relationships, then cheating would be a lot less common.
Consider if the spouse stop loose interest in sex with you.
Adultery has legal repercussions in the family court. So you are both ethically and legally obligated to swear an oath of abstinence, because the spouse isn't going to put out. A lot of times spouses will manipulate their partners with the sex understand these circumstances. That is why I have no contempt for people who cheat under such circumstances.
This is just another reason why marriage is silly and irreconcilable in the modern era. It's like trying to reconcile slavery by enforcing 8 hour work days and minimum wages. Marriage should stop existing and in its place people should be making explicit agreements about the nature of their relationship. Not all relationships are one size fits all.