Yes, it’s always difficult for outsiders to weigh the blame when two people divorce.
But we’re talking about divorce and re-marriage. Even if someone is divorced against their will, and is not to blame for the divorce, they are still committing adultery if they decide to remarry. That remarriage is their decision, freely made.
Very difficult and unfortunate. But life isn’t always fair. Just because life is tough doesn’t give anyone a right to commit adultery.
Jesus says someone else causes it