Remember that one random girl in the early chapters that he gave all his money to, for her to cook and make new delicious dishes? Well, it turns out she was the creator of this world and the final secret boss after the demon king (not the goddess).
She knows him irl long ago and he owes her money, but he forgot. Just like he was planning to send the game to the dude that owed him money, she created the game to teach him a lesson the same way, trap and get back at him.
When he finds out, he is mad and goes to fight her, but she is literally unbeatable, all of his team try to stop him, but he is too strong so they can't, then most of them die, half are killed on purpose (the good ones), the other half sacrifice themselves to save him (the original 3), the other heroes are dead by this point and only Frilly is alive.
At the end she returns him in the real world. He really apologies, returns her money and asking her out on a date. Last scene instead of deleting the game, he plays again.
