The Hulu series “Alice and Steve” has many aspects of a romantic comedy: witty banter, protagonists with quirky creative jobs and a set piece centered on a dinner party. But the namesake characters are not, in fact, the lovebirds whose ill-advised union serves as the show’s inciting incident. They’re two middle-aged Londoners whose decades-long best friendship is put to the ultimate test when Steve (Jemaine Clement), a divorced and childless celebrity hairstylist who yearns for a nuclear family, starts dating Izzy (Yali Topol Margalith) — a woman who’s half his age, and also Alice’s (Nicola Walker) daughter.

Yet “Alice and Steve,” which was created and written by Sophie Goodhart (“Rivals”) and directed by Tom Kingsley (“This Is Going to Hurt”), is aptly named. The lived-in platonic chemistry between Walker and Clement is the show’s highlight and its foundation, keeping the action anchored in something wholesome amid some abominable behavior on both sides of the friends’ growing rift. Steve, of course, is having sex with a woman he’s known since she was a small child, a point “Alice and Steve” touches on without dwelling too long, lest this become a much bleaker show. (Steve also insists he’d never been attracted to Izzy before a spontaneous encounter in Alice’s living room, and the scripts repeatedly emphasize Izzy as an active and enthusiastic pursuer.) But the crisis his poor judgment induces in Alice ends up unmasking her ugly side, and exposing cracks in her own marriage to the sweet, mild-mannered Daniel (Joel Fry).