I guess | felt like it was a combination of both, and that didn't necessarily ring THAT untrue to me? I would imagine they were very aware of the theme of toxic masculinity, they made it clear that Cliff and David were the kings of their own universe in different ways.

I felt that Cliff's choice not to be intimate with his wife in his robot/clone form was a sign of respect and that he did love her deep down despite not knowing how to express it. I also felt like the relative safety of the isolated farmhouse was maybe his way of thinking he could protect his family, whereas David was basking in the attention he got in his town without it ever occurring to him the family could be in danger.

When David and Lana go into town to buy art supplies the interaction they have with the cashier was so creepy, you feel that society's ugly underbelly would have maybe come for Cliff's family before long (and yes it was crazy stupid they just let the clones live without security in the houses - Black Mirror requiring bucketloads of suspension of disbelief on this one!).

Anyway great, thoughtful analysis, I can see why the ending was so divisive, they kind of painted themself into a hole but I felt like it was sightly less predictable than had he killed Cliff. I guess basically they both chose their own survival in the end, even if it meant likely eternal misery, so maybe their toxic masculinity came home to roost in a way?