A closed bedroom door is not an insult. Sometimes it’s just a person recharging.

A closed door gets read as a message, because people read nearly everything as being about them. Most of the time it is maintenance: somebody is tired, or overstimulated, or needs twenty minutes without being spoken to before they can be pleasant again. Reading it as rejection invents a problem that was not there, and then the door has to carry a conversation it never started.

Ask rather than interpret, later and lightly, if you are unsure. And when yours is shut, say once what it means: I am fine and I need an hour. One sentence saves everybody a lot of guessing.