For every bracing and original work in which couples deftly exploit public curiosity for the purposes of complex cinema (Tom Cruise and Nicole Kidman in Eyes Wide Shut ), there are as many if not more flops (Ben Affleck and Jennifer Lopez in Gigli, Brad Pitt and Angelina Jolie in By the Sea ).

Dave Franco and Alison Brie have made the midnight movie of the year. At January’s Sundance Film Festival, no selection was more raucously received than Together, a body-horror thriller about a relationship that gives new meaning to the term co-dependent.

The perils of the dating scene are vast, but there are horrors in long-term relationships too. With intimacy and commitment, there can also come codependency and even convergence. Once individuals, some couples start to dress alike,