That person is cheating on their first spouse, biblically their only spouse.
Luke 16:18
“Everyone who divorces his wife and marries another commits adultery, and he who marries a woman divorced from her husband commits adultery
I’m not saying you’re wrong but I thought that verse was specifically referring to people who leave their spouses in order to marry someone else. Respectfuly I must ask, does that rule still apply to forced marriages, people with dead spouses, or people who divorced their abusive or unfaithful spouse?
Dead spouses fall under “to death to us part”. They’ve died, you’ve parted, you can remarry.
In the other two cases, you’d need an annulment, which seems applicable here. Especially for a forced marriage, since that specifically goes against the precepts of holy sacramental marriage.
Obscure Fandoms 