Love Is Strange, directed by Ira Sachs, is one of those quiet movies that, like a Michael Cunningham novel, sneaks up and punches you in the face, just as you were thinking “What does any of this add up to?”

Alfred Molina and John Lithgow play a couple who have been together for 39 years and, as the film opens, are finally getting married, an act that precipitates Molina’s character being fired from his job as a music teacher in a Catholic high school. That’s just the setup; the film is so far from being an issue-of-the-week movie, that, although everything that happens flows from that original injustice, it soon becomes about other, more interesting things.

Primarily, the cycles of love and how we survive each other. It’s a movie about friendship and, being a quintessential New York story, a movie about real estate. Lithgow, as 70-something-year-old Ben, is retired and on a pension, and Molina, as newly unemployed George, is without funds. Having enjoyed a certain standard of living, they are suddenly, shockingly thrust into penury.

There are, of course, more urgent deprivations on the spectrum, but it’s a circumstance that rings very true: the apparently affluent who are actually flat broke, on the brink of old age, and desperately vulnerable. George and Ben’s only option is to sell their apartment and crash, separately, at the homes of friends and relatives, who love them up to a point, that point being having them around all day. The interplay of tensions between those trying to help and those trying not to be a burden is exquisitely and tenderly done, with a fine, subtle humour.

Love Is Strange also does something a lot of movies fail to do, which is to place the central romantic relationship realistically in its social context and show us how all of our relationships are informed by the examples of the relationships around us.

And it exposes the limits of how much we can help each other. There is a scene in which Lithgow, ejected rudely by his nephew’s teenage son from the bedroom they are forced to share, walks into the living room where the parents are huddled in private conference; the sense he communicates of knowing he’s not wanted but having nowhere else to go will break your heart.

Molina is always a joy to watch and there are some very strong supporting roles, for instance Marisa Tomei, as Ben’s niece by marriage, loving him despite being infuriated by having him under foot all day, is wonderful. And the angry son, played by Charlie Tahan, is the best teenager I’ve seen on screen in a long while.

But the movie is Lithgow’s. He just played King Lear in Central Park and blew everyone away. His performance in this film will make you cry and remind you that while kindness has a cost, there comes a time in life when it’s all that there is.

• Comments have been reopened to time with this film’s Australian release