Still not forgiving him for what he did earlier you tell him that you have homework to do.
Still mad at Darien you decide to make him suffer, "Well it sounds nice, but I have umm homework to do, yeah homework." Darien looks disappointed and says, "Okay, I've got to go study for an exam anyway." With that you both walk away in different directions. On your way home you bump into Luna. "So did you have a good day, you didn't have to fight the Negaforce today." You don't bother to answer. When you get home you take one look at the pile of homework you have and flop down on your bed, sleeping the rest of the day away.
This is one of the seven endings, as the rating goes you didn't too well with handling Serena's love life, our personal recomendation is that you start again and make some different choices, and see if you can't get one of the more appealing endings.