YA Fiction: large group of people that live in a type of facility where they are chosen who they live with

[Jordyn]

*spoilers* I read this book in either late elementary or middle school, I'm in high school now. I Think there are two main characters, one female one male. it takes place in the future where people are assigned wo they will be with/ marry forever. Doesn't matter if you have feelings for them or not. The female main character didn't like that idea because her twin sister was secretly in love with the guy she was assigned to. They switched places by changing their tattoo, maybe trackers. I'm not to sure about that part but the female main character then went with the guy her sister was assigned to. Then, skipping ahead they find this device that can open any door. towards the end of the book they found this huge robot while trying to escape. It lead them to a dark black void of a room where she saw a ladder, she climbed up and I'm pretty sure it was just white. So yea that's all I remember, and would love it if anybody can help. I really want to read this again.

[Becca]

Above the Sky by Jenny Lynne?