>>213330605
If you remember, a big aspect of K. is his desire to be "real" (not a replicant), although it's also a fear because his resignition to being one provides at least some safeguard to the morality of his actions. His one solace in life his is AI gf he bought and pretty much spends all his money on. She "decides" to give him a "real" name: Joe. K. believes, she's different, "like a real girl", just like he's different. So when Joi is destroyed while Luv says "I do hope you enjoyed our product" (she's says this while looking at Joi, which might suggest she's calling K. the product) he's even more devastated. At this point of the movie K believes he IS human that his memories are real, and it made him question all the suffering and immorality he swallowed just because he believed he didn't have agency. But after losing Joi he learns that they're not his memories, that he was never real at all, something he had previously been resigned to but having that taste of hope and freedom just made it much more bitter.
So when he walks in the rain and sees a giant advertisment of a naked Joi say "You look lonely[...] You look like a good JOE" it just fucking destroys him. She wasn't different, she was just a product, he was never Joe; he never anything but a replicant. His love was never real. And this creates a resolve in him to actually die for something real: Deckard and his daughter, from which he had gotten his memories from.
