She didn't go - that was the penultimate episode. In the final episode the Doc got her head xrays which showed a possible bleed. Mad dash to airport, blagged his way on to the plane (elbowed everyone out the way) and he rushed her to hospital.
He did her brain surgery, she made a good recovery. It ended when he told her she was going to be discharged from hospital but she didn't have to come home. She said she couldn't go back to the way they were. Cue curtain