So, the fact that they've known each other since childhood makes the time frame for this romance palatable to me but the fact that they don't communicate well with each other makes me a bit leery.
Clay seems to have loved Mar from afar for a long time, which makes it plausible that he'd jump when her father calls and says she's in danger. And yes, we know as readers, that the "she's only a job" isn't going to hold for long. I don't understand why it took Clay so long to ask her why she never responded to his attempt to ask her to prom. I can understand why as a teen, and feeling rejected, he might not have approached her about it, but to go years?
I both like and dislike their teasing of each other. Sometimes I think the teasing was used to hide things that they should discuss and that I didn't like. But there were times that it was used to ease a tense moment, and I do think couples can have some teasing in their relationships and have it show that they are comfortable with each other.
I have a hard time believing that Clay could set up a security system but never think to look for tracking devices or bugs. I mean even Mar realizes someone could track her via her cell phone and has it off.
I liked the twist in who it was that was really doing the threatening.