^ Yeah, I'm not sure if Ayu ever confirmed that herself, but that seems to be the most likely cause.
It is pretty twisted that both showstopper-type performances from the past two tours ended up getting the axe before the end, but both were quite personal songs (Return Road for obvious reasons). Emotions/personal issues getting in the way is an inherent risk when you intertwine your art so closely with your life, which Ayu has always done. And though it's irritating, I can't honestly say I'd want her to stop doing that, haha.
I just really hope this doesn't become a trend.