I'm sure the sure-thing girls didn't zing with Rentarou because their eyes are closed because they are always smiling for reassurance, hence "Sure-thing" girls.
I bet if we are very lucky, I mean really lucky that we would get to this point of the anime in the future, this will be put in an OVA series or something.
It feels like these giving hints and taking it back is her way for him to chose whether he wants to change a little to be able to be side by side with her or chose a path which he'll never change and be burned along the way.