He is in denial.
All it will take is a bit of flossing and several glasses of water a day. It is dehydration breath from too much instant coffee and breathing in and out of his mouth. It smells like dog poo. He goes to the dentist so it isn’t bad teeth.
I have tried for years to kindly drop hints but he refuses to believe me and thinks I’m being rude. I want to sleep in the spare room. I’ve had enough.