Agree with M0nica, it's likely to be hoarding disorder. The trouble is that it's 'synhedonic', in other words, it doesn't upset the person because they have little insight into their problem. They only see it as YOUR problem. I have lived with this. Late husband was an academic and his room at the university was completely full, to the extent that when he had students for tutorials, he had to book a study room! When his department moved buildings and he was told he could have only 2 filing cabinets in his new office, all the stuff came home. We had a very big study, and I confined it to there and the garage. Every time I vacuumed I found stuff behind the furniture. I told him I would throw out anything I found. He told me I had an obsession with tidiness (ME?). His former professor even included his hoarding habits in a poem read at his retirement. He was a dear and lovely man though, and there was so much to offset his problem. He did succumb to early-onset dementia (but note that the hoarding was lifelong) and eventually, when we had to move, his son and DIL came up from London and got rid of about 3/4 of the detritus, for which I was grateful. In retrospect, I would say I had been too 'understanding', but it is a really difficult problem, and it's your call how you deal with it. You might have to threaten divorce, but he will need help of both carrot and stick!