He wants me to fly out to see him. How do I know he's seriously invested?

I met a guy at a wedding a month and a half ago. We hit it off and have talked every day since, even though we're 11 hours apart. He mentioned a few times wanting me to fly to visit him. How do I know that he's serious/invested? What are your general opinions or advice?
Updates
+1 y
We haven't discussed cost. I'm assuming I would pay for the ticket and he would take care of whatever happens there.
He wants me to fly out to see him. How do I know he's seriously invested?
Post Opinion