Going after a taken girl is a safe bet, because it means a guy is willing to put up with them. That means the crazy level can't be that bad..orr the sex is just that good. With a single girl you never know what to expect. Like why is she single if she is so hot? Crazy is the answer.
Nick, I love you, but I will have to go against you on this. This is a much different circumstance than having a job is the best way to get a job argument. Unfortunately, we have close to literal apes running around the planet, looking to find a semi-moist hole to stick their prick in for the first time; and once they do, they intend to keep it that way. Just because a girl has a man, doesn't mean she's worth sticking your cock in more than a couple times.
Also, I've seen New Girls' photo... She's no Rachel, and won't be around long. #missboss