Romance Novel (Camally Oneshot)

Your sons recently started going to the school a few blocks away and you bring them in to the library every day after school while you wait for your wife to come pick you all up because you only have one car. I love seeing them because your boys are adorable and cheerful and actually pretty well-behaved, and always take a few minutes to tell me about their days at school when they come to sign up for the computers. I love seeing you because you're hot, and obviously very good with them, but also clearly married and- Oh, wait. They're your nephews, and it's your sister who picks you up every day?