I think any marriage is save-able providing both parties really want to work at it.
If I gained a lot of weight, started neglecting my oral hygiene to the extent my retainer had blood on every morning, asked my husband to smell my belly button finger and excavated wax from my ears in front of him - and then straight refused to change any of those things about me despite him asking me to change.
if I didn’t pull my weight around the house, left dirty crockery lying about and licked my plate in front of the children - and then refused to change those things…
then both parties are not working at it.
his oral hygiene thing sounds flipping horrendous - being a junk food eating slob is really unattractive - and the belly button thing is totally beyond the pale..
I think we cut people far far far too much slack in contemporary culture for living unnecessarily sloppy lives. There is a direct correlation in my experience - of people that are emotionally / professionally successful - and tidy lives. My successful friends and family aren’t all super slender - but they are universally capable of maintaining good personal health routines + running a basically tidy home.
if you don’t want to be mired in a slightly slovenly existence with him then something has to change.
Does he need some proper mental health care? If so then he needs to seek that and make effort to engage with treatment
does he take you seriously when you express concern / that you need change?
would he be open to couples therapy?
if he won’t change + won’t join you in figuring it out together - then you must leave. Because we do only get one go at life. And I think it’s too precious to waste eating KFC everyday and failing to brush your teeth.