Owen tries the "it was just meaningless sex" defense - a line that never seems to work, yet guys always fall back on - to explain away his cheating on Cristina in a new clip from tonight's Grey's Anatomy.

These two have been heading down a dark road for awhile now, and from the looks of things, it's going to get a lot worse before it gets better ... if it even gets better at all. There's no guarantee anymore.

Check out the four Grey's Anatomy clips we posted yesterday for more glimpses of what's to come in "The Lion Sleeps Tonight." Then watch the minute-long sneak peek from this evening's show here:

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.