[jimhefferon]

At that time, in those jurisdictions, you could only get divorced under very precise circumstances. One of the few ways was for one spouse, typically the woman, to assert "extreme cruelty."

I don't know any more about this divorce than anyone else here but I do know that at the time people did whatever it took to fit in the required "extreme" criteria.

[CamperBob2]

It was also a matter of mutual agreement; sometimes the husband and wife would agree to accuse each other of crap like that. You know you have terrible public policy when couples are incentivized to slander each other in order to separate amicably.

[Turing_Machine]

Another common ruse was setting up a fake adultery with the help of an accommodating friend. One spouse would take a picture of the other spouse and the friend coming out of a motel room. Instant grounds for divorce.