I see that many people have added your book to favorites, but haven't commented. Here's what I think of your book (don't be worried!)
So, I loved the plot, the story was really captivating and emotional. The characters were well developed and I loved how you brought back each characters memories of each other at just the right time. The ending was also amazing and realistic enough because of your characters past and personalities.
I have to say, though, that you had quite a few grammar mistakes and missing words. This is not a big deal, just make sure to have someone edit it for you later. Also, toward the end, there were some confusing scenes that need to be more clear. You can keep the suspense and mystery, just help the reader understand better who is talking at certain times.
Don't be discouraged by the critique. I truly loved your story and can't wait to read the next two when they're up.
-me ;)