It’s been in the news! Here’s how to stop it: make the “default” for marriage be sexless. That is, when you get married, you commit to your partner and also that you will only have sex as many times as needed to have children. In other words, marriage is sexless.
Then husbands and wives won’t cheat outside of marriage, they’ll cheat within marriage. They’ll cheat with each other! What fun that will be!