Guys, What does it mean when a guy brings up marriage hypothetically? Ex: “well what if it was us who were married, would you think the same way”?

We see each other casually, but exclusively, and live in different states. He also gave me a key to his place if that means anything?

Guys, What does it mean when a guy brings up marriage hypothetically? Ex: “well what if it was us who were married, would you think the same way”?
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