It seems to me that having an affair pretty much clobbers the whole menagerie, not just the puppy.
I have been taking the "kicking someone's puppy" to mean waiting until the guy exposes his vulnerable side and then dissing him, insulting him, ridiculing him, aiming an RPG directly at the vulnerable spot.
For example, comparing him to a past (better) lover, making fun of something he's sensitive about in front of other people, responding with hilarity, anger, rudeness in a tender moment.
I'm not denying that an affair hurts the other person, but if we go back to the original statement that this is all about, if I recall, blcakfoot implied (or outright SAID) that sooner or later a woman will wait until your puppy is exposed and then kick it to the curb. If we apply that only to affairs, that statement seems to say that sooner or later every woman will cheat on her partner. That certainly isn't true.
And it also isn't true that sooner or later every woman will lull the puppy into a state of false security just so she can kick it. THAT attitude is not good for romantic R's or friendships. It's the equivalent of women who go around male-bashing all the time. I've had a few women friends like that and I've ended our friendships, not JUST because of that, but because people who go around bashing the opposite sex are (in my experience) gloomy, crabby, whiny, tiresome martyrs who spend most of their time complaining about SOMETHING.
