The first two are grammatically correct, but I'm guessing they don't mean what you're trying to say. They literally mean, "He doesn't love her as much as she loves herself." If I understand your intended meaning correctly, I would suggest: He doesn't her as much as she loves him.

#1 and #2 are grammatical. Without context, it is not possible to say what they mean because one cannot tell to whom "she" refers. "She" and "her" could refer to the same, or different, people. #3 makes the most sense if "she" and "her" refer to different women. In that case, it is a good sentence and means that he does not love her the way that the second woman loves her.

^^^ He doesn't love her as much as she loves him. ^^^

He doesn't love her in the way she does

He doesn't love her the way she does