"But baby, we only kissed once... That's not cheating"

Yo yo yo!

How are ya dahlings? I'm pretty good - can't wait for Friday so I can stay home and rest go out and play. So I had a conversation with my friend the other day, and the subject of 'Cheating' came up. He said it's only cheating if you've had sex with someone who isn't your significant other... kissing and more doesn't count as cheating in his book. This friend of mine can be very sarcastic, so I'm not sure if he was joking or not. But of course, I decided to ask around and consult 'them.' Them being my online dictionaries, innit?

My Comrade friend 
Cheating is spending intimate time with someone other than your partner

My Hairvenly friend 
There are 2 categories. Emotional (having an emotional relationship with someone else even if there's no physical contact involved) and Sexual (kissing, making out, having sex)

My Kingly friend
Cheating is spending time with someone you're attracted to, knowing your partner would not be happy about it - or even keeping it away from your partner.

My Cakesy friend
Cheating is doing something with someone else that you know your S/O would be unhappy about.

My IT friend
You know you're cheating when you're doing something with someone else and you feel even the tiniest twinge of guilt.

My Dictionary friends (Oxford et al) 
To be sexually unfaithful

Somewhere online
It's only cheating if you're caught

I once heard someone describe cheating as "Engaging in any activity with someone of the opposite sex, that you would not otherwise do, if your significant other was there." This is more in line with what my human friends have said about cheating. I think I agree more with this perspective. If you're doing something with a guy/gal who isn't your S/O, and you know you would NEVER do it if your S/O was around, then it's cheating (or as good as cheating).

I saw this survey online (where else?)

Disclaimer: I don't think flirting is cheating... if you do it the way I do, which is innocent and does NOT lead anybody on. :p

What do you think constitutes as cheating?