You're assuming the transgression is against the woman, which is clearly not what the OP meant.

More to the point, this kind of "no sex with coworkers" mentality has many of us Europeans rolling our eyes at the New World. It's absolutely possible to both respect women and have sexual encounters with people we meet at the workplace and do so in a professional manner.

There's a huge difference between playful, consensual flirting and fucking on the photocopier. My experience is that the people who fail to make these distinction constitute -- in fact -- a highly ideological minority.