Was this guy actually interested in me, or was I just part of his post-breakup/vacation phase?

I'm 25F ("Ella"), and there's a guy ("Steven," 29M) We are not biologically related—our families are connected through marriage. We've only seen each other occasionally over the years.

Fast forward to this summer. We were both on graduation trip for a younger family member in Mexico. I arrived three days after everyone else and left three days before the rest of the group.

A few important details:

He had broken up with his girlfriend about three weeks earlier and found out before the trip that she cheated on him.
Early in the trip he flirted with another girl and got a hickey, and after I left the trip he ended up going home with another woman he met at a club.
Despite that, throughout the 5 days we were together he seemed to gravitate to me.
Some examples:

He sat next to me at meals multiple times.
He remembered seeing me at a football tailgate months earlier and specifically remembered me playing beer pong well, even though I didn't even remember he was there.
He repeatedly started conversations with me about school
and dating.
He told me about his breakup and later asked if I was seeing anyone. I told him I wasn't because grad school keeps me busy, he smiled.
After I told him I thought he was very good-looking and charismatic, he hugged me.
We developed several inside jokes that he kept bringing back over the course of the trip.
He complimented my shoes.
He offered me his chair multiple times.
He gave me drinks, accepted drinks from me, and we even shared sips of each other's drinks.
We teased each other constantly.
He would sometimes catch my eye from across the table or room and smile.
He talked about seeing me again at the football game (November) and said he'd try to make a Fourth of July family gathering.
On the other hand, after the trip he didn't come to the Fourth of July party, even though he said he'd try. About two weeks later I sent him an Instagram follow request. He left it pending for a week, then accepted it and requested to follow me back.
Was this guy actually interested in me, or was I just part of his post-breakup/vacation phase?
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