And as I've said these are not "marital problems" by any standard human definition. They're not just "growing apart", Jean is no longer entirely human and getting less so with each flap of the Phoenix wings. She's a quart of godhood in a human pint pot. You can't "relearn" each other when one of you no longer speaks the language.
There IS no possible resolution of that that, divorce was losing any meaning for Jean as much as marriage was. And we HAD already seen her throw herself at Logan trying to get some sort of reaction out of Scott.
It was adultery of a sort I agree, but Jean picking through Emma's mind and deliberately opening up raw emotional wounds because she no longer understood the human notion of sympathy or empathy any more was just plain warped.