Another possibility is that Kat already is giving Phil almost all of her money, and that Phil can't ask her for more. Maybe they fight over this because Kat feels that she's working her ass off and doesn't get to keep anything for herself. If they are fighting over this, Phil might get triggered by the suggestion. I think this is more likely the case.
Kat giving Phil most of her money would also explain why she was crying about the Twitch partnership loss. Perhaps she feels the end is near, after Phil went bankrupt and is still demanding she pay bills, now faced with a possible huge reduction in income. Maybe she changed jobs because Phil wanted her to make more money to help out with bills. I think its safe to assume Phil lies to Kat about his money as much as he does to his viewers.