I disagree. God doesn't punish the faithful partner in a marriage just because sins. There is biblical cause for divorce and its adultry.
You don't understand. I am not against divorce nor do I believe there is a complete prohibition against it in the Bible.
However, without a doubt, there is no excuse for your adultery when you have sex with someone else while your vowed spouse is still alive, even if he or she left you in a divorce.
Your spouse cannot make you break your vow to God. But you can do that when you have sex with another.