Sister and friend

His sister is one of the creators who wrote his blooming book that was based on ML but abusive.

His sister is madness. (Unintentionally)
She made/wished this world to save her brother life looks nice but it's also cruel cause she is dumb.
She trapped him in a fictional character. And programmed a way (script) that every time MC remembers his real past, he will suffer of amnesia and endless pain. And also every time he doesn't do what that fictional character would do he will experience this cycle of suffering. That why he goes back to a "dumb" MC.
So even if the sister tells her about his past or about this world. The script will take over.
All of above it's kind of nice of his sister.

She gave him false hope that what I hate about her. It may not be intentionally but cruel.
Remember that MC only remember his sister not even his own self. Leaving him hope/desire to return, to her, to someone who is ALREADY dead.

His friends are also kinda harsh but understandable. His friend didnt want to return to the real world cause of sad abusive past family or something. He knew about the whole system and was scared to tell MC the truth, it could send him back if this artificial reality collapse.