I totally get this, and mostly am of the same mind. However, there is a catharsis that I think some other people are seeking from having her show up, and be totally crushed by the mistake of letting him go/treating him poorly. I understand the desire for that, even if I don't feel like it's something I would personally include. Not important for the story, really, but could prove to be an emotionally satisfying moment for some.I really don't have any interest in meeting the mc's ex girlfriend. Why waste time with someone that already proved that she can't be trusted?
Moot point, though, given that (based on what other people have said, I'm not about to dig through this enormous thread to verify) Killer7 has said it's absolutely not happening.