If I was with a girl and some fuckhead ended up sleeping with her, I would end up rearranging the dude's face. That's just the way it fuckin' goes, bud, there's just things you don't do, some impulses you do not act upon, or there will be consequences.
I'm kinda verging into devil's advocate territory here but is punching a dude in the face not just as primal an impulse as wanting to stick it in a hottie? Or is this a case of one act of caveman-ism deserves another? I realise that one act is despicable and the other is considered "defending your honour" or some shit, but the whole justified-violent-retribution thing never really sat well with me in any situation. Short of somebody causing great intentional, undeserved pain or anguish to a very close friend or family member, I can't think of anything that would drive me to find somebody and (attempt) to beat them into a pulp. I just don't feel like it would fix anything, nor provide any personal relief from the emotional pain.
@Cronopio:
I basically agree with everything you said except the face smashing bit, obviously hahah. Physical pain isn't a substitute for emotional pain, and it's not gonna teach you to be a better person. Maybe I'm totally wrong here but if some dude wrecked me for cheating with his girlfriend, I'm not gonna sit down the next day and be like "actually he made a very good point and I can now emotionally connect with him," I'm gonna be like "CUNT that shit hurt, I'm not gonna go there again." Sure it taught me not to fuck with HIM, but it didn't teach me not to fuck with some pussy-nobody who isn't capable of defending himself.
When I got together with some other dude's chick a while ago it wasn't his phone and email threats that made me realise what a tool I was, it was talking to the girl (and eventually him) afterwards, and experiencing their pain.
To clarify, I'm not trying to suggest that infidelity is by any means reasonable or acceptable. The shittiest I've ever felt was after being cheated on (which sort of shows what a comparatively easy life i've had in terms of emotional trauma), and I wouldn't wish that on anyone. It's experiencing that pain both personally and through somebody else that led me to grow up. Maybe getting beaten would have done too, but I doubt it.