Toras Moshe: Why are you bringing it down from the Rambam (the things that a mans wife has to do for him), bring it down from the Gemara in Kesubos Daf Daled amud Bais (4b) that says “All the things a woman must do for her husband, a nidah must do for her husband EXCEPT for Pouring his drink, making his bed, washing his face, hands, & feet” Therefore we know that generally she always has to do it.
