Let Me In movie question?

After seeing the movie Let Me In, I was very puzzled by the ending. Does Abby truly love Owen or is she just using him so he could take over Thomas's role? Did Owen want to leave with Abby at the end or did he reluctantly go? Because the way he looked out the window on the train, he looked sad to leave. Also, when Abby saved him in the pool scene, he didn't look grateful that Abby saved him but scared. I really hope that the feelings between Abby and Owen is mutual because then that ruins the romance in the movie. Please answer all of these questions as detailed as you can. Thank you.