TT, social preconceptions about the ethics of having sex with people in relationships aside, any idiot can see that this girls "relationship" is either so flimsy as to be inconsequential, or doomed by her own ditziness/sluttiness to fail badly, and soon...and so the normal debate about whether or not youll undermine/destroy a "relationship" is moot - since she is going to fuck it up waaaaaaaaaay before you do (already has, really. sending naked pics = BEYOND breakup offense)
also, in my experience, ive found that girls in "relationships" who hit on other guys very hard (naked pics etc) have the mindset of a single girl, but have been pushed/trapped in a flimsy relationship by some insecure/clueless guy trying to manipulate them into exclusivity that they dont want. therefore, its your job to RESCUE HER!!
i love morality arguments lol
oh. yah. what slat said. now. nownownow