I am in a similar situation. She calls me two times a day and looks discontent when I don't call her. So, I am always available when she needs me. I know that time could change everyone and everyone's decision.
My personal opinion is that there's no need to interrupt the friendship. If she starts dating just tell her that you couldn't continue being around. Or if you prefer do not tell her anything and stay away, pretending that everything is ok. Meanwhile, if a lovely woman come up in your life do not miss the chance.
