Judging by how hard it was for Ruby and Saphire to stay appart in hit the diamond (the only time they were defuesed where they weren't seperated or mad at eachother), it might be possible that a sort of 'fusion addiction' happens if two gems (or people in this case) have enough of a connection and are fused often enough/for long enough

Hu ho, seem like she not only took her martial skills from me but also my thirst….. That can't be good.