My first instinct was to say Twilight mixed with Men In Black but that's not quite fair.
It was a fluffy star-crossed teenaged lovers (who are not actually having sex). Our human girl is book smart, a loner and also is brave to the point of stupidity. Our alien boy is quiet, intense, and spent the last 60-70 years on Earth being 18.
Not at all like Twilight. My apologies.
Anyway, I actually did enjoy this little book. It was not a bad way to spend an afternoon at all. Just don't expect any real substance. It's junk food and there is nothing wrong with that.