Uninvited by Amanda Marrone

What's on the back of the book:
When rejection comes back to bite you . . .

Jordan hates her life! Her boyfriend Michael dumped her, hooked up with half the other girls in the neighbourhood, and then killed himself. And, if that wasn't bad enough, her life now consists of a succession of boring parties, meaningless flirting and friends she can't relate to. But now, somehow, Michael is back, appearing at her window every night, begging her to let him in.

Jordan can't understand why he wants to get back together; he was the one that dumped her! But, as the weeks drag on, she feels her resistance wearing down. Instead of partying and socialising with her so-called friends, now Jordan runs home to the safety of her room before dark, and waits, alone and terrified, for the sun to go down.

Creatures like Michael need to be invited in before they can cross over the threshold. All Jordan has to do is say the word . . .

A piece from the book:
"Jordan, let me in."
"Go away, Michael. I will never let you in." My voice is steady and calm, without emotion. I've said these words a hundred times today, so they'd become automatic. So I wouldn't change my mind.
Michael sighs, and I think I see him nodding. He knows I'm not ready to let him in. I suspect he knows I think about it, though. I suspect he knows that a part of me wants to.
"You don't know how good you have it, Jo."
I don't like where this is leading. This won't be a "let's talk about the future" night. Michael's missing his old life and he'll keep me up for hours if I encourage him.
"Did you go to school today? Did anyone talk about me?"
I roll my eyes. "This is high school, Michael, you're old news. People have found better things to gossip about. I mean, dying in the summer . . . well, your timing was way off. If having people remember you is important, that is. There's just way too much happening, people move on pretty quickly. Now, if you had died during the school year, that would have made a bigger impact."
"God, Jo! This isn't easy for me, you know."
I nod and wonder if his eyes see better than mine. Can he see I'm putting on an act, that every inch of my skin tingles when he sits outside my window? "I'm sorry, Michael, but I'm tired. I need to sleep."
"But I miss you, Jo. It's not like you think. I can't sleep. I can't sleep at all. I'm awake with nothing to do. Nothing to do but think, and miss you."
"I'll leave some books outside for you tomorrow. Maybe you can accomplish something you never did when you were alive - you can actually read a book. Or, hey, how about this? You can walk into the sunlight and end this all. Have you thought of that? What would happen if you walked into the sun?"
Michael's quiet, and I think he may keep it short tonight - until he taps his foot on my window.