Yes, divorce didn't exist back then, but you could still be decent and not cheat. Jane did have a problem with it, it's not like she agreed to be his mistress. It still worked out for them after his wife died, but I still don't like Rochester. He could have done a lot of things other than lock her up in the attic. Like the famous farm houses which hide a lot of secrets. She might have even benefited from an Asylums which did exist. Still, for Jane it all worked out for the best in the end and I look at what happen to Rochester as his punishment.