1) I think it would make a difference, but not be the determining factor.
2) I tend to be very forgiving, and find it difficult to bear a grudge or be angry at anyone for very long. The only way I could really push away someone I would term my "significant other"(not the easiest person to connect with, so anyone that close to me I would value greatly)that cheated on me would be if they were utterly unrepentant and did it because they believed, in their minds, the relationship to be over (but didn't bother to send out a memo). In short, if it wasn't going to work anyway and I knew it.
On the other hand, I also have to admit I have none too small a paranoid streak and a hyperactive imagination; so maybe I would be able to patch it back together in the short term, but no mental extrapolation/simulation can tell me if it would stay together for days/weeks/months after.
3)Male.