Dynasty

Tied by a string and unable to let go - they were friends and a thing but never a couple, they were on and off. She knew about his flings and she had her own, she was there for him as he was there for her but as she settled he threatened to turn her life upside down.

Why did he have to wait till she was finally happy and she had let him go? Had she let him go? Why was the pull towards him so strong if she thought she had let him go.