**SPOILERS**
I read this as I was looking for something else to read, that wasn't in my norm. The first couple of chapters were interesting, the black box on the back of her head, the idea of just time travel for the mind sure. I couldn't buy her love for this guy and that she was this upset that she would go back in time just to get even. This character is obviously on the spectrum, so for her to not understand the emotions of a relationship, but then have such an explosive reaction to a breakup didn't make sense to me. Then also, I felt cheated at the ending. For someone to go through all this effort to breakup with a guy, and she just tries to kill him for 100 days, and he doesn't die or she doesn't actually end up insane I felt misled. This wasn't designed to be a book of happily ever afters.
The author also plays with multiple theories of time travel rather than just one, so that also didn't appeal to me, as someone who has followed the different theories. This book shoves a lot of science in the reader's face at once and hopes that just keeps you. It did, but I didn't enjoy it afterward. I want stuff that makes sense. Sure you have the science, follow through on the science presented.