**** A Separation A superb work of realism by Asghar Farhadi about a youngish middle-class Iranian woman (Leila Hatami) who leaves her husband (Peyman Moaadi), putting his sick father and their studious and astute 11-year-old daughter (Sarina Farhadi) in the uncertain middle. The request for a divorce sets in motion a chain of small domestic events whose dismaying implications accrue. In Farsi, with English subtitles. (123 min., PG-13) (Wesley Morris)