everything_but_the_word

We're basically a couple until I call us one

Two years. They sleep at my place three or four nights a week. We have groceries we both buy. There's a charger on their side of my bed. My neighbours know them. We have a stupid Sunday routine involving coffee and the crossword. If I describe our life without saying what we are, everyone assumes we're a couple. But if I call them my partner, they correct me. Last night I asked what the actual difference would be between what we're doing now and being in a relationship. They said, "Expectations." I asked which expectations. They couldn't really answer. Eventually they said they don't want to feel responsible for somebody else's happiness. I don't think I've ever asked them to be responsible for mine. I want to be able to book Christmas without wondering whether mentioning December is going to make them disappear for a week. I think I've spent two years trying to prove I can be close to them without requiring anything from them. Has anyone actually managed to move from this kind of setup into a relationship, or does the fact that the label itself scares them tell me everything I need to know?