well she was pretty back in the day (like before and right when they got married, but now? looking like her mother too much and way too young to be!
pretty simple reason i think in regards to their separation: i mean he wants to go into acting again and he wants to get laid by young nymphos in his late mid life crisis,
she?: no longer has to act as the good wife and 1st lady of california, she's tired of his roving eye, his body is gone, so there is no sexual attraction for her, she loves his money, but doesn't really need it, probably wants to work herself more.
maybe too simplistic, but it seems to be this way?