Annoyed

Maybe he has realised at last that you had a point,and he is missing you,and decided he will do it because HE has decided,not you asking him
Men are like that, stubborn

It may be nothing to do with his teeth.
Halitosis can occur when there are stomach problems or other disorders.
Can you urge him to visit a dentist and/or a doctor?

Callistemom, I had asked him loads of times to go. He finally went after the plane incident, he got a course of strong antibiotics.
The point is tho that his diet is high fat and very meaty and he eats that all day and didn't clean his teeth at night.

Sounds as though , now that other people are mentioning it , he has decided to do something about it.

Will this help your marriage though or is it too late?

Is it all about more than the bad breath.?

Narnia I really feel for you.
A course of antibiotics won’t help chronic periodontal (gum) disease which is the most likely cause of his bad breath, though as Callistemon says there could be other causes.
Different people have different bacterial flora in their mouths and some produce a worse odour than others.
Tooth brushing & mouthwash will help up to a point, but if he has periodontal disease with gum pocketing, he will need to see a dental hygienist for deep cleaning of the pockets.
Try to persuade him to do this. It could benefit his general health too, as it’s recognised that there’s an association between periodontal disease and heart disease.
Good luck.

He must be incredibly thick skinned to ignore you when you first mentioned it. Your question seems to be why has he started brushing his teeth now that you are in separate rooms. Well I would imagine that it's not for your benefit and he doesn't care so someone else? I would think that you need to sit down together and discuss where your future lies. This is obviously about more than dental hygiene.

I don’t think it’s at all helpful to make assumptions & speculate that this has anything to do with anything other than Narnia’s DH’s oral hygiene.
People only change their behaviour when they perceive some benefit to themselves.
Narnia’s requests to do something had no effect because he couldn’t or wouldn’t accept the impact he had on other people.

But he has found out that he doesn’t like sleeping by himself and by making an effort with his oral hygiene he’s hoping that he’ll be able to resume their usual arrangement.

He should see a dentist. This doesn’t sound like it can be sorted by teeth cleaning alone.

You should urge him to see a doctor about it if he wants to keep his job and his health.

I have a bacteria that lives in my gut and sometimes get bad breath because of it . I brush my teeth and use mouthwash but two minutes later it’s as bad as ever. My family and very close friends have been told by me to tell me to eat a mint if they can smell it as I’d rather that than just be smelly !

Does he have a hiatus hernia with heartburn especially at night ? That can also cause bad breath.
I'd guess his diet doesn't help at all with this problem.
Maybe, now he's in a room on his own, the smell, to him is more noticeable so he's started the night time teeth cleaning or just doing the stubborn little boy thing of not doing it because you have asked him to!
Either way, he should see a dentist and his GP to get everything checked out. I'm surprised that none of his work colleagues have commented if he's that bad!

See a doctor
Friend had poisonous breath for years... Oral hygiene adequate..
Unfortunately died very unexpectedly with liver abscess..

I know that people who follow a strict Keto diet (practically no carbs and very high in animal fats and proteins) say bad breath is a problem they have at times due to the ketones exhaled (when your body is burning fat as an energy source you produce a lot of ketones which have a very distinct and unpleasant smell). Obviously not cleaning his teeth will not help but could you perhaps persuade him to eat more fruit and vegetables and see if that helps?

Narnia,could’ve been me writing that. For ten or fifteen years my husband was the same.
Dentist said teeth were fine. I bought very expensive mouth wash,he always brushed teeth twice daily, but zero result.
Then he was struck with pneumonia, put in an induced coma, and on life support. Loads of antibiotics etc, and he pulled through.
His breath is perfect now, and still is 7 years on!! What on earth could last fifteen years and not “self heal?”
Something is very off further down. A good course of a decent antibiotic will hopefully solve it! Tell Dr whole story, hopefully he’ll give it a go for you.

Best of luck, please report back if you solve this problem! ???????????

He should start with the dentist. Having had gum disease myself, I know how bad it can make breath. Left alone, he will lose his teeth. If he won't go to the dentist, get him to invest in an electric toothbrush and inter dental brushes or floss. Once that is sorted, good dental hygiene can become habitual. If things don't improve, then further investigations can proceed.

I feel for you. My husband is the same. Has not visited a dentist since he was 14 and has absolutely no intention to do so now. Despite having an electric toothbrush with a timer, I know it is only in his mouth for a few seconds (I can hear it), sometimes, only once a day. Sucking mints have no impact at this stage. He would not listen to any suggestions to go to a dentist, so I don't try.

Bad breath to that extent could be stomach or bowel problems/disease. Hopefully he will finally accept some help

Don't want to alarm you but he should go to the doctor as it could be something serious causing his bad breath. And definitely a dentist.

My husband too! I suggested dentist. Like talking to a brick wall. Then again only seen an optician once in the last 50 years! I nearly forgot the hearing problem.

I've given up suggesting any sort of appointment. Simply no point. He carries a breath freshener spray around now!
Waste of money ?

Has he been tested for the H pylori bacteria. My friend had this a few years back. A simple test at the G.P surgery. Her breathe had a certain smell. All cured by a course of strong antibiotics. I would think a trip to the dentist adviseable too

Smelly breath does not seem to be the issue since H has decided to do something about it so ask him why he no longer appears to want to share your bed.?

Whilst I’m not implying Narnia’s husband has this particular illness, I am more sympathising with the predicament.
During a period of ‘not speaking’ (I married a sulker!) my husband caught what he thought was a cold and he filled Every room in the house with the smell of his bad breath. Although I told him his breath was very strong, he couldn’t smell it and therefore it didn’t exist! Every room he went in smelled like, dare I say, dead flesh after he had been in the room! In the end the smell became so bad I insisted on taking him to A&E as clearly the smell of rotting flesh was not right. I was heaving with the smell as I drove him to hospital and had to have the windows open - although it wasn’t much help. It turned out he had a bad case of pneumonia and had fluid on the lungs and ended up in hospital for two weeks. He lost a lot of weight (yippee!) and was very poorly (☹️) but recovered.
Bad breath has other more serious implications than just lack of hygiene so if the dentist can’t find a problem, the next step should be the GP. Sometimes the bad breath is simply caused by rotting food stuck in between teeth and simple flossing dislodges the offending culprit.
To have suffered with his bad breath for so many years shows a strong commitment to your partner so is it possible if his breath no longer smells, you will have a happy marriage moving forward?

My brother has horrible breath that I cannot ride with him in a car. He has gum disease which is causing this. He won’t go to a dentist now and his teeth have fallen out.

I think that some people are missing the point - the OP was asking why has her husband changed his habits now - not asking for halitosis cures. Which he probably has no interest in pursuing.