I thought it would be something like Gone and The Lord of Flies . Something like chaos. Instead, it falls more into romance than Sci Fi. The beginning was the best part. Everything else afterwards was boring. The ending felt so abrupt, I felt like I was reading a sample. I had to go to Wikipedia to double check, that yes, the book is done. There were a lot of flashbacks, at least one in every chapter. 
 You know how, when people draw, someone sketches a person and often leaves the background blank? That's pretty much all the world building in the story. Everything was so vague, it felt so colorless to me. 
 This is how pretty much everyone is like: nobody stops to think. 
 (view spoiler)[ 
 There's this character, Wells. He finds out, that basically, the person he likes is going to die. And of course, his dad was going to send out an expedition to earth. He has to speed the process up. (How could he have known that the leaders were going to send jailed up teenage convicts - which the person he loves is among - to earth? What if it was a group of volunteers?) 
 So for reasons unknown, in a flashback, he goes somewhere, cuts something with a wrench (a plier? wire cutter? something like that, Idk) and somehow lets the oxygen leak out. Just so his father could send people to earth? There were really no other alternate options? Flash to right now, it's just like the Titanic: the upper class gets separated from the lower classes, because of the lack of oxygen. 
 (hide spoiler)]