How do we make a shared home when everything already has a place in my flat?

My partner put his father's wooden chair beside the window. I moved it into the spare room the next morning because it blocked the bookshelf. When he came home, he said, "I thought I lived here now."

He moved into my flat last month. We had talked about the big practical things, but I hadn't realised how often I was saying that a lamp, print or shelf wouldn't go with what was already there. This time I had a practical reason: I use that bookshelf daily. Still, I moved the chair without asking.

His father made it when he was young, and it was the one piece of furniture he especially wanted to bring. I like the home I've put together over several years. I don't want to throw away everything because we now share it, and he hasn't asked me to. He wants some choices that don't start with asking whether they fit mine.

How do we change the rooms together when one person's version is already fully built? The chair is back by the window while we figure it out.