Super interesting point that struck a chord with me. Without the risk of rejection, the ai will come off as a sycophantic ass kissing yes-man. It might be seductive at first but will get old fast for most people, I would imagine.
What would be really interesting is how much longer the relationship would last if it were formed on a social media site or forum where there is still some risk of rejection, and validation from others still has the feel of being earned.