It's a New Adult / YA Paranormal book came out in the last year or two. Pretty sure it's the author's first book.
Re-colonized Earth now populating 1 of 3 planets (or 2 planets and a moon). Earth young adults (girls and boys) traded / given to the other 2 planets in payment for re-colonization or for materials. One group is for slaves other to become warriors. Best friends (boy and girl) gets separated to different classes. The girl is given to 2 leaders. The ending is a cliffhanger where the girl escapes trying to get to another zone on the same planet.
Re-colonized Earth now populating 1 of 3 planets (or 2 planets and a moon). Earth young adults (girls and boys) traded / given to the other 2 planets in payment for re-colonization or for materials. One group is for slaves other to become warriors. Best friends (boy and girl) gets separated to different classes. The girl is given to 2 leaders. The ending is a cliffhanger where the girl escapes trying to get to another zone on the same planet.