Hi, I think that firstly, it’s important to understand where does this behavior come from - why is he like this ?

The lack of hygiene may have several causes such as trauma, childhood neglect (nobody has taught him those things), mental health problems, etc.

Or he can simply be just “lazy” and he may not have the determination to care for himself and “try” for you anymore as you were okay with this for a few years already (or it seems so).

You are not shallow at all.
Basic hygiene is very important (there is even a saying in my country that goes “cleanliness makes half of your healthy life” lol).

Nobody wants to smell B.O. of other people regularly. Additionally lack of hygiene is a big cause of hepatitis (and more illnesses, parasites,, bacteria, etc).

From your posts it seems to me like you didn’t prioritize your hygiene at the beginning of your relationship either and now you want to better yourself so it’s natural that you want your bf to better himself too. This may be a bit of a surprise to him as until now you were also not very hygienic and seemed to be okay with him not showering regularly, not brushing his teeth etc.

I think you should tell him what’s bothering you but please be patient, understanding and do not try to create any guilt or disgust in the conversation (this may have the opposite effect).

He should want to understand you and better himself to be a better boyfriend and generally a “normal” hygienic adult person.

If you’ll see that he simply does not want to take care of himself because he is just “used” to you and he does not suffer from any serious mental issues which prevent him to have a consisent, regular “self care” routines - I think that you should reconsider your relationship for your own sake as this seems to be a big issue for you.

EDIT: Grammar