A Faithful Man
In this French dramedy, a couple's relationship gets tense when she leaves him for his best friend, and then returns to him after that friend dies.
"Marianne leaves Abel for Paul, his best friend and the father of her unborn child. Eight years later, Paul dies. Abel and Marianne get back together, arousing feelings of jealousy in both Marianne's son, Joseph, and Paul's sister, Eva, who has secretly loved Abel since childhood." (San Sebastián International Film Festival)