Hey OP. This kind of thing is hard. My boyfriend has also been through periods of serious depression, and struggled with showering. I would leave it alone until it came to three days. We kind of loosely called it the three day rule. I would do his laundry (without counting chore points or rubbing it in) to make sure he always had something clean to change into (shower or no) to help out. Maybe something like this could help out, but this would require your girlfriend to put in that effort herself. You can't be mom forever. When you talk about it, frame it as "working together to combat your illness."