I do think that a woman will stop making an effort when she wont have any atention anymore from the partner, sex will be just monotonous( maybe many times just him coming)nice words wont exist anymore.
If the woman is not making an effort, man will start to feel unappreciated, will wonder whats wrong, she will wonder whats wrong, stop speaking to eachother and so.
I would say both partners have a fault.
Is a very large subject.