My Childhood Sweetheart's Brother

Abbie has been with Dan, ever since she can remember. She met him at 5, had their first kiss at 6, shared a birthday party at 8, had their first sleepover at 10, school disco at 11, first date at 13, started the same high school at 14, and lost her virginity to him at 16. Why wouldn't she stay with him forever? Afte...