I've namechanged for this.
A bit of background to start off.
To all intents and purposes my DM and I have a good relationship. She left my step-father a few years ago for another man, which caused a bit of an upset in the family. Since she's been with OM, she has radically changed her personality - enjoys different things, acts and speaks differently, moved country, looks different. If that's what makes her happy, it doesn't matter a jot, although I suspect she has had long-term problems with loving herself and always trying to please the man in her life ... But that's a story for another time.
OM clearly favours the "natural" look in women. He writes things on Facebook about how women shouldn't shave their "bush", for example, so he's quite overt about his preferences. DM stopped dying her hair, stopped using shampoo and conditioner, and also stopped using deoderant. (He also doesn't use these things as far I know.)
At first, she was really proud of the fact she had freed herself from the "constraints of consumerism" and waxed lyrical about how much money she was saving by not buying into the beauty industry's marketing cons. Both DSis and I sort of laughed along, but pointed out that without deoderant, she was starting to smell a bit. She assured us she didn't, that only old sweat smells, and that as she showered twice a day and always changed her clothes (not we saw any evidence of this when we were around her), she did not smell. She had previously been fanatical about appearance, by the way.
Fast-forward a few years. The smell has got worse. So bad, in fact, that their whole house stinks when you walk in. The family all talk about it behind her back (not in a bitchy way though). She works in quite a professional setting, and I can't believe that her colleagues won't have noticed it.
I slept in a bed she had been in for two nights the other week (staying with family). Even though the sheets had been changed, the smell made me retch 
One of my teenage cousins refuses to give up her room for them anymore because the smell is so hard to shift.
I spoke to an aunty of mine to ask whether or not I should tell her. She advised doing it very gently, and perhaps leading with a question about her health, so I didn't embarrass her too much.
The response I got was very weird, but maybe DM was just highly embarrassed. She told me that yes, she knew she had a problem, but that no one had ever mentioned it to her before. She said the menopause was causing her so many problems that she was in hospital for tests. I immediately felt awful for saying anything, and gave her a hug and said it wasn't that bad anyway. She asked me not to mention it again because she felt so dreadful.
So I haven't. But I've seen her once since, and the smell was definitely better. So my question is, does this happen in the menopause often? I know I was very sweaty during puberty, so I can quite imagine the hormones doing horrible things during menopause, too. What kind of tests could she have been having? Or is it more likely that she lied when I asked to save face? I can understand why she would have done, because I would be mortified, too, to be told I smelt. But if she is actually ill, I want to know.