FWB is a well-crafted comedy of the sex-first, romance-later genre that — bonus! — isn't blatantly nonsensical. Mila Kunis and Justin Timberlake star as Jamie and Dylan, who meet after he relocates from LA to New York. Each is raw from a break-up, with Jamie comically blaming movie love stories for her misery. The first act is about banter and movement, and culminates in the pact to "have sex like we're playing tennis," with no expectations or guilt. The second contrasts carnal pleasure with awkwardness outside the bedroom. In the third it's time to, in the spirit of the '90s references, "start getting real." A familiar trajectory, but director Will Gluck keeps it interesting by letting the characters' feelings emerge at a believable pace. Most important, Kunis and Timberlake really do have chemistry, as well as comic timing. When his tender glances meet her sly conspiratorial smile, it's genuinely fun to watch.