I guess in a manner of speaking I have been cheated on. Tis a bit complicated though.
However, I have never and will never cheat on anyone. Because I'm not a coward, if I feel the desire to stay at all for any reason then I'd own up to it rather than start sneaking around.
That being said that probably wont happen anyway since it's statistically highly improbable that I'd (a) find someone and be in a relationship in the first place, and (b) find another person like that at some point in my life then, (c) that person being just as - if not more - awesome than the guy I'd already be with.
Given my impossibly high standards, finding a single guy even worth my time would be a miracle, finding two would mean that clearly I'm just having one of those weird **** reverse harem dreams again and then... well, then things would get XXX hardcore pretty quickly.
So, yeah, no. I'd never cheat because they'd never be anyone else worth cheating on my figurative boyfriend with anyway. Once I find the right guy I wouldn't do anything like that to him, I'd treat that lucky **** like a King. But, if it wasn't working out for some reason then I'd be upfront about the whole situation. In a manner of speaking, I'm far too blunt and straight-forward to cheat on anyone.