What Counts as Cheating in a Marriage?

So, how do you define cheating when you're married?  Is it sex?  Is it kissing?  Is it emotional intent?  I want to talk about each possibility but first I will give you the answer to what cheating is:  

If you have to ask, it's cheating.  Well, more accurately if your spouse thinks it's cheating, then it's cheating.

If you think you cheated because you held hands with another girl then you cheated.  If you think you didn't cheat because all you did was kiss, then move on to step two.  If my wife found out about me trying to sleep around on her, she'd consider that cheating.  Personally I don't think it's cheating unless I'm touching a girl in a way I wouldn't do in front of my own wife.

Is Sex Cheating? Seems an obvious, "yes" but I know a person or two who thinks sex isn't cheating if it's purely physical and there's no emotional connection.  These are the people I need to spend more time with.

Is Oral Sex Cheating? If it's good enough for Clinton, it's good enough for me.  Putting your junk in someone else's mouth or worse, licking another woman's privates is pretty personal.  Some would probably think this was a deeper connection than simple sex.

Is Kissing Cheating?  Ever date a girl who thinks that kissing is only for people who are in love and will let you sleep with her but not kiss her?  I have.  She was insane.  Some people think very highly of kissing.  To me kissing is cheating because I wouldn't do it in front of my wife.

Is Flirting Cheating? I say no, flirting is fun unless you're planning on going further.  I flirt with girls in front of my wife, it only makes her have sex with me to "keep me close."  

Is Falling in Love Cheating?  Since getting married I've met plenty of girls who I think "if I had met them first, they'd be the one."  I'm not leaving my wife for them and they're not the kind of girls I'd try to have an affair with but I've had some pretty serious obsessions with girls who are not my wife.  This is probably the scariest type of cheating to a woman.  If I get drunk and sleep with some slut my wife would be pissed but she would think I still loved her, if I fell for another woman even without touching her... woo.