Just because something is legal doesn’t mean everybody likes it. George (Alfred Molina) and Ben (John Lithgow) discover this for themselves in “Love is Strange.” After four decades together, the men can finally marry in New York, but the bliss doesn’t last long. George loses his job teaching music at a Catholic school as a result of his marriage, and the couple must sell their apartment. Finding another place where they both can stay proves challenging, and George and Ben are forced to live apart until the world returns to its normal rotation. Lithgow and Molina have apparently been friends for ages, but this is their first time working together; the chemistry is obvious. Molina, in particular, is in fine form here. “Love is Strange” tackles a thoroughly modern problem in a pretty familiar way, anchored by a couple really nice performances.