At Bright Lights Film Journal, Joelle Kidd delivers a thoughtful essay on I'm Thinking of Ending Things and men writing women:

I’m Thinking of Ending Things is, like so many stories, a story about a man masquerading as a story about a woman. Which ultimately makes me wonder why we need to spend so much time trying to figure out how to build a better mask. I was disappointed when Lucy disappeared for the final section of the film, not because there was no longer a female character on-screen but because it felt like the moment when the film ceased to grapple with the implications of what it means for a man to craft a fictionalized woman to suit his own narrative, his own purposes – the very thing, of course, that Kaufman is doing, the thing that male writers do, by necessity, all the time.

[...] Charlie Kaufman has the talent, rare even among artists. of the ability to surprise. His films often reveal the assumptions we as filmgoers have about the nature of movies – for instance, the assumed 1:1 relationship between character and actor. Subversions of this have taken place throughout film history, with a single actor playing multiple characters, or multiple actors playing a single character. But what about a character who not only has multiple identities but perhaps no fixed identity? Can a coherent character, who seems like a person in all the important ways, be created out of many people, many personalities? (Source)