I'm pretty much with CSL here but will add..

Jesus pointed out to those there at the time that Moses, not God, gave the Jews their law for divorce. Jesus made it quite clear that the only condition you can remarry under is that your partner dies. Anything else is adultery.

I don't know that looking at porn is grounds for divorce. It is adultery ('He who looks at another woman with lust has already committed adultery in his heart" or similar words) to sleep with a person other than your partner, unless your partner has died - hence the "till death do us part" in the traditional vows.

God Bless,
TC