Nora Ephron’s iconic romantic comedy “When Harry Met Sally,” from 1989, posed the age-old question of whether a heterosexual man and a heterosexual woman can ever be just friends—and came down staunchly on the side of “nope!” “Platonic,” a new comedy series on Apple TV+, goes the other way. The show, created by Nicholas Stoller, stars Rose Byrne and Seth Rogen (reunited after playing a married couple in Stoller’s “Neighbors” films) as Sylvia and Will, a pair of old drinking buddies who have fallen out of touch. In the meantime, their lives have accrued emotional mass: Sylvia is married with children and feeling restless, Will is schlumping through a painful divorce. When the two reconnect, they give each other permission to lean into improvidence; they get high, they destroy property, they carouse. The one thing they do not do is sleep together; this is a show about lost youth, not lost love. It is always good to see Rogen, who has emerged lately as a kind of majordomo of chill (see his Instagram devoted to his weed business and his ceramic creations), but the show really belongs to Byrne, who is at her best when she plays a woman severely in need of a good time.