Starting Over Talk - Peer Coaching Support Site

I hope I have this under the correct topic. I've only recently started watching the show and am not sure on a couple of background matters. I can't recall the characters names yet either, sorry, but... The female doctor who's last name is Grey I think, she is dating one of the surgeons at the hospital. That surgeon is married. Did the female doctor not know he was married or was he separated when they began the relationship? Can someone explain?