I see a lot of people answering this as if it's a bad thing that this is happening. It's disappointing to me that people don't think for themselves and just go along with traditionalist ideology. Marriage is based on the lie that you can be sure you'll be in love with someone for the rest of your life.. the heart doesn't work that way. Love doesn't work that way. Everything changes over time. So it's a good thing if people are getting more divorces. They're being truer to their hearts. If it seems infidelitous, it's merely insincerity matching insincerity (the insincerity of the idea of marriage). It's a healthy reaction to a false premise.

Marriage is also a kind of contract whose purpose is to feel security by insuring that neither partner will leave the other--even if it would be the natural thing to do. And as soon as two people are bound to each other with this kind of security, the romance is killed. The spark is replaced by mere familiarity.