Longing (2018)

Ariel, a well-off, childless man, gets a phone call from his college girlfriend. She needs to tell him a couple of very surprising things: first, when they broke up twenty years ago, she was pregnant and went on to have a lovely boy. The second thing will make Ariel explore the hidden aspects of parenthood and change his life forever.

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