Even before we found out that Diana was directly involved in secret plots with Nate's grandfather and Chuck's father, watching her seduce and defile our beloved Nate gave us the heebie-jeebies.
Okay, so "defile" is a strong word, considering he had already had an affair with a married woman by that point, but you get the general idea. She was creepy, and Nate behaved like a horny, slobbering teenage boy. It was gross, and it lasted for far too long.
Keep on clicking through for more horrible TV couples!