Declutter snd indulging in negative emotion

So I’m having a lot of trouble with this month’s work. I have gone through most of my stuff (not all) but I’m really realizing how much I’m feeling like this house is definitely not mine. When I moved in here, I really only brought my clothes and nothing else. Everything in this house does not belong to me, no kitchen stuff, bedroom stuff, furniture, nothing. I am living with a partner who owns a lot of crap and when we are to go through our rooms one by one and declutter them, I don’t feel like it’s my business to go through his drawers where nothing in them belongs to me. Do I just go through stuff on my own without regard for him or get him to do it with me? Do I just focus on myself and not worry about the house stuff since none of it’s mine? I want to clean up this house and don’t know how to move forward. I also think the house is extremely nonfunctional, the layout is tettoble and I don’t want to live here forever as it is outdated as in all the flooring is dark and cupboards are dark. I feel like this month’s work is obviously what I need in my life since I’m having such a difficult time with it. I need some help!!!