YA & NA Romance ♥ discussion

I’m not sure if anyone can help but I’m looking for a certain book I’ve read before but I can’t remember the name or author. It’s about a young girl who is afraid to leave the house. She becomes best friends with her sisters boyfriend (I think it’s her bf). The girl is a huge reader and he always comes over and talks to her about everything. The guy isn’t really into the sister from what I remember. Eventually the guy gets tired of waiting for the girl to admit her feelings and he leaves. I think he becomes a pro basketball player or something. Sorry I can’t remember the plot very well lol