There’s nothing wrong with giving your significant other little reminders about their personal hygiene. I’m not saying you should do anything drastic like waterboarding them with mouth wash until they agree to brush at least once a day, because I’m at least 50 percent sure that’s illegal in a few states. Tell them they’re a disgusting pig some other way that results in less screaming and crying.
I guess no matter what there’s going to be some degree of screaming and crying, which is why you need to be clever. Make her think that it’s her idea, and you might be able to get away with it. Otherwise you’ll be sleeping on the couch for the next century.