Theory: Rey is a child of the force (or a Kenobi)  and will fulfill the prophecy that Anakin was never able to fulfill which is to stabilize the force. Also, in a reversed sense compared to Anakin, Kylo Ren can be restored to the light through his compassion for Rey.  
Logical reason for shipping reylo; 
In the book, Kylo Ren is told that he has compassion for Rey by Snoke, which in Anakin's words, is the path to love. It necessarily does not have to be romantic, but, i'm a teenager so love is always on the mind ;)