This is a swell alien or quasi-alien romance story. It's also the first book by Jennifer L. Armentrout that I've read. I liked the fact that the characters and their relationships and their dialogue sounded pretty fresh and realistic. I cared about the relationship that our heroine had with her possibly-scary alien amour and it felt quite sparky like you'd want and expect in a romance.
I guess this is an offshoot of a series about these "Luxen" alien invaders, so previous books would have been more centered on the intensity and conflict of that, I suppose. Here, you really have a very YA tale about a girl not fitting in and trying to understand her world. The sci-fi and fantasy elements are basically decoration for that essential tale.