He is her soul mate in her travels and wanderings. He did not leave her for a moment, and he never abandoned her. Rather, their relationship became stronger after the illness, and they endured the exhaustion together.
They both were like a medicine that soothes the pain until they became a "lifeline" for each other.
They were together and pledged to stay that way, but life sometimes forces us to take an unplanned road that can't be avoided, so the memories remain the most beautiful consolation.