Start yelling and freaking out on Darien and Rai.
You start to flail your arms and yell at Darien and Rai, "What are you two doing? What are YOU two going out now. Rai you've always been jealous of me!" Rai stops laughing and looks at you, and then laughs again, "Me jealous of you?" You are too mad to say anything so you wait untill Sabastien has rowed to shore and then tell him that you remembered some homework you have to do. You start walking home, but just as you get out of the park Darien runs up behind you and says, "Serena, I'm really sorry." You look at him and tell him, "You shouldn't have paid so much attention to Rai." Dairen smiles "I know, and I'm sorry, it's just that seeing you with that other guy made me jealous" You smile back at him. He leans over and kisses you. "How about I take you out for dinner to make up for it." So the days ends well and you get to enjoy a nice dinner with Darien.
This is one of the seven endings. You did pretty good at managing Serena's love life. Well done.