That's part of the 'happy' ending and it's played as a joke. Yes, their whole situation is fucked up, but what happens once they've gotten out of it is portrayed as a positive. Maybe in your reading you were able to maintain a dark tone in your head (or maybe it doesn't have the epilogue style thing I'm referencing) but in the official audio version the characters are joking, laughing, and moving on with their lives, including Kyle and Kimber remaining a happy couple after becoming well aware of the more direct nature of their relationship