Grace and Frankie Season 1 available May 8 on Netflix.

Jane Fonda and Lily Tomlin play the title characters in Grace and Frankie, which combines a superficially progressive premise with some creaky sitcom construction. In that way it reflects its main characters, two women in their 70s who have to figure out new ways to live their lives when everything they took for granted comes crashing down. In particular, Grace and Frankie’s respective marriages to law partners Robert (Martin Sheen) and Sol (Sam Waterston) fall apart, when Robert and Sol reveal their two-decade-long affair with each other and declare their intention to get married. The uptight, type-A Grace and the laid-back, New Age-y Frankie find themselves living together in the beach house that the couples jointly owned, having to rely on each other for support.

That leads to a lot of familiar odd-couple jokes, which combine with the clueless-old-people jokes to make up a good 50 percent of the humor. Co-created by Friends’ Marta Kauffman, Grace and Frankie has an old-school sitcom sensibility even though it’s a single-camera show with no studio audience and features the occasional F-bomb (because it’s on Netflix). That contrived wackiness doesn’t serve the more serious parts of the story, especially when the writers try to sensitively portray Robert and Sol’s relationship. Sheen and Waterston are completely unconvincing as a gay couple, and since their ex-wives are the main characters, they too often come off like the villains. At worst, Grace and Frankie is a show about how tough it is for straight people when gay people finally muster the courage to come out.

At best, it’s a showcase for the chemistry between Fonda and Tomlin, who 35 years ago co-starred in 1980’s acclaimed comedy 9 to 5. Their banter can be fun, and they can also bring out the pathos in these women who are facing multiple challenges in their twilight years. That genuine emotion doesn’t come out often enough, though, and the storylines featuring the main characters’ grown children are mostly dead ends. Unlike Amazon’s Transparent, which deals compassionately with a late-in-life revelation about sexuality, Grace and Frankie is mostly content to recycle old jokes in a new context.