The willingness to live in make believe, and the willingness to treat that make believe as if it were reality.
This disconnect from physical reality, and the substitution of a fantasy world for reality, is at the root of the overwhelming majority of millennial mental health issues... Video game, phone, and internet brain damage...
To the extent that generated images replace human porn, I don't see that as an issue. Perhaps it's even a positive in removing some potential exploitation of porn actors. But I don't think most people think of porn as their "girlfriend".
In the same sense I don't think many women think of a dildo as their "boyfriend".
But in both cases there are some people who think of interactive generated images and audio as a relationship partner. These are the cases that are based on a disconnect from reality, and lead to (or are a symptom of) further mental health issues...