Every exchange student who has made it the entire year will tell you that a little past the half-way mark they realize that they want to stay. Instead of thinking of how far away going home is, they think of how soon leaving is. They realize that they may run out of time before they're able to do everything they dreamed of doing. They think of leaving their new friends and families and are reminded of how hard it was to leave home what seems like a lifetime ago.
Chloe says she doesn't want to come home, but I think she means she just doesn't want to leave. That's not so different than when she first got to Pamplona when she said she didn't want to come home, but wished all of her friends and family could go there. If she were suddenly faced with the prospect of never returning home, she'd probably have a much different opinion. Just imagine how our world would change if we were able to travel great distances in minutes and at little cost. Then she could combine her Spanish world and her world here into one fabulous world.