How do I ask him what we are?

“What are we?” can carry several questions at once: exclusivity, commitment, expectations or a name for the relationship. Naming the part you want to clarify gives both people a clearer question to answer.

Your own wish can come first, followed by a direct question about his. The aim is a shared understanding, not a phrase that makes agreement inevitable. An unclear response leaves the issue open rather than silently deciding it for either of you.