Some of the above people have said exactly what I'm thinking.
Having a chaotic house with heaps of stuff in it doesn't make you less of a person. You don't have to live in a sterile - oops sorry minimalist hehe - environment to be a great person. Who cares if your cupboards are full? Well, of course he does but you deserve someone who thinks a full home is a sign of a generous loving heart. You don't have any dead cats hiding under piles of collectables so seriously don't let this guy turn you into such an unhappy person trying to live up to what he considers is the benchmark. Find someone who appreciates that you have exactly what they need tucked away in some corner waiting to be needed
PS Adding on: In agreement with some of the other posters, it's one of the incompatiblilties which are impossible to overcome. You would always be miserable trying to live up to his standard which is wrong as you should never have to live up to your lovers expectations. You probably already are miserable.
It's not about whether you should have a go at decluttering your life because you'd do that if it was right for you. You are who you are and there's nothing wrong with that. Just at the moment it's presenting a bit of a problem for you in finding a way to get serious with your man. I don't think it's worth living on edge all the time because he can't stand that about you. But then, maybe you would feel worse not having someone in your life even if it's only ever going to go to the level you currenlty have.
<3 good luck and I hope you find your answers