What if Catherine had cheated...

DIVORCE

Even scripturally speaking he's not obligated to stay with her. Teachings directly from Jesus:

Matthew 5: 31-32
It was also said, ‘Whoever divorces his wife, let him give her a certificate of divorce.’ 32 But I say to you that everyone who divorces his wife, except on the ground of sexual immorality, makes her commit adultery, and whoever marries a divorced woman commits adultery.


Jesus is teaching against divorce, that if one divorces and marries another they've committed adultery because marriage is a life commitment.....not a "contract" to get out of. The only disclaimer he gave was "except for sexual immorality" You aren't commanded to stay married to an unfaithful mate.

I have seen marriages restored even after a spouse was unfaithful. God is the center of every marriage because He created it.