Messy partner - really need advice
So I have been with this person for a good while now. We have a lot in common and they're the best partner I've ever had (I've been in a lot of relationships). I'm anxious and depressed at the idea of us breaking up because of how amazing and loving they are. They have so many good traits and are an incredibly good person. We are both in our early 30s.
We're both on the spectrum but they also have adhd, which I don't. My autism and the way I was raised/household I lived in have made me into a very clean and tidy person. I am no ocd like neat freak, but my space always being tidy and organized is a priority for me. It brings me peace and happiness and I get very stressed when my place isn't tidy. Messy for me is not having dusted places that are hard to reach for a while and having clothes in a bag or hamper that are clean but have yet to be put away. I'm the kind of HAVE to make the bed every day type of person.
Their audhd makes it incredibly hard for them to maintain a clean environment. It was pretty decent when we first started dating but then got progressively worse as the months went by. I constantly feel anxious and sad being at their place when it looks like that and have a hard time being there. Because of our work schedules, I have to go to their place 90% of the time or we'd barely ever see each other. They're a full time, hard worker so I know that also makes it difficult to keep a clean house.
They are bothered and deeply ashamed by the mess. They also want a clean and tidy environment. I have tried to help several times by cleaning things myself, but their place has gotten so bad that it grosses me out to do it now since I don't wanna be around/touch said mess. I offered to pay for a cleaner but they don't want a stranger in their house and are also too embarrassed by the way it looks to have someone else see it.
They sometimes get defensive and silent when I mention the mess. Mention as in me trying to seem ok but they notice that I'm off, so they ask what's wrong and I tell them the truth. I have stopped bringing it up myself and have always tried to do so in a careful and compassionate way as to not upset them in the past. A few times they have cleaned up stuff that bothered me right away though. They said that they told me multiple times that they need help with cleaning and I always say ok, so let's do it right now together (or on the day it's brought up) but they're always too tired from work. When we do clean together it's great, but it's never enough because of how much cleaning the space needs and because they struggle to clean for too long. I have a hard time cleaning up on my own or after them because of how bad the place has gotten and then I feel guilty about not being able to help clean more in depth. Because I would never let my place get that bad, it's extremely difficult for me to be in that environment, much less touch/clean gross things from it. I was always able to when it wasn't this bad.
I don't know what to do anymore. I love them deeply and don't want to leave them but I struggle to help when it's gotten to this point. I also gaslight myself about the place not being that bad so I can hopefully look past it for the sake of the relationship.
Tldr: long term partner is very messy and I'm not. I don't wanna leave but can't take it anymore and it's becoming too hard for me to keep helping with the cleaning despite wanting to and having done so in the past.