Gateway by Christina Garner
Everybody has their demons. Some are just a little more real than others...
Ember has always known she doesn't belong in this world, but when she tries to correct the mistake, she wakes to find herself in a mental institution.
There she draws the attention of Taren, a mysterious boy who isn't what he seems.
When chaos erupts, they are forced to flee the institution together, and the secret Taren has been keeping, brings Ember closer to understanding her own.
And leads her to... the Gateway.