I watched it. It's slice of life so I can't get over that. It's so quiet. They weren't really talking about their feelings.
From the novel wiki, Elio sleeps with Oliver, then Marzia (the girl) then goes back to Elio. It's like he tested the waters of whether he liked vag or cock, hehe.
In the movie, he slept with the girl twice before staying with Oliver.
I was tickled that Elio's father had a gay experience too, hehe