If i catch her and she didnt tell me prior to me finding out. Yes that is cheating all the way! Now if we already talked about it and im okay with it. Thats a different story.
Cheating as in our relationship is being replaced by her next one...then yes.
If she has the need to scratch that itch our relationship is such that she knows I'd be willing to help with the close encounter of the third kind...I'll hold the Iphone!
My wife is the straightest woman I have ever known, so the odds of this happening are rather long.
I would say no, as this is a fantasy of mine. Then again I can only speculate how I'd feel. Reality sometimes doesn't meet up with expectations.
If she tells me first, or has a pass, its not cheating.