Trio (1967)

The lives of three young people in their teens are linked through their experiences in this drama from director Gian Franco Mingozzi. A girl wins a pop singing contest and begins a successful career, at the same time taking on various lovers, discarding them at whim with no regard to their feelings. A curious teenage boy spies on the lonely bachelor who lives across the street and observes that he always has a handful of bills, so the boy decides to rob him. When the boy can't go through with the crime, he seeks out the bachelor to teach him something about life that the teen feels he is missing.

Unfortunately the movie Trio is not yet available on HBO Max.