thank ya, my dear! :)
things are definitely not all black and white by any means, and i think people are very much able to change their behaviors (especially since many of us did some REAL dumb shit in our early- and mid-20s).
the ongoing emotional connection would certainly be an issue, but like i replied to Mr. Winstonalden above, it's possible my ideas on the concept are tainted because of HOW MANY of my exes have cheated on me; i just can't tolerate it anymore, no matter the reasoning behind it. but that's just me. it's a completely relationship-ending act as far as i'm concerned. my trust, at that point, is gone and pretty unlikely to return, which isn't healthy for the remainder of the relationship should it continue.