How do you spot when your being strung along?

I think I have been strung along on and off for the past eight months by my ex gf. It didn't always appear that way and at times she appeared genuinely confused whether to choose me or her current bf. She wants to stay friends now which IME would probably be FWB.

Are there clear signs of being strung along or is it more the case of you know when someone is CLEARLY interested in you and only you?