Willow actually set me off a lot earlier than that this time around. Narratively, I think it was a problem for her character that Joss couldn't figure out how to write in college/careers; too much of her characterization has to fall away to let her stay living at Buffy's house through her early twenties, and I think it leaves an unsettling emptiness underneath her wide-eyed sweetness, a trait that worked for me when she was the smart girl but less so when she seemed to lose all life direction. What at first reads as protective coloration started to feel manipulative for me by mid s4.