The problem with Vaughn is that Sydney sees him as her "soul mate," but he has frequently acted like a jerk. He was married and not showing any sign of leaving his wife, yet he acted like a jealous, possessive fool when Sydney admitted that she slept with Will, that it was a one-time thing, but that she was moving on. I'm expected to love him for "not being able to help" having feelings for her . . . but how about feeling irritated at him that he can't realize and accept his damn feelings and get out of his marriage and get with the woman that he so obviously prefers?! There is such a thing as divorce in our society, after all! Damn, man! Add to that the one-way honesty street he runs with Sydney, expecting her to tell him all her secrets while he keeps whatever secrets from her he finds convenient . . .
The whole marriage thing didn't sit well with a lot of fans, I suspect. For me, Vaughn was obviously subconsciously looking for a way to avoid dealing with his grief, telling himself that he was "moving on," when in fact, he hadn't gotten to the point where he could. It's hard for me to respect a man who doesn't have the courage to face his own emotions, and it's hard for me to look at Vaughn's marriage in any other way.
Sorry if this sounds harsh, but frankly, I've found myself becoming more and more irritated with the character and I've actually written them asking them if they want me to like the character. If they do, they need to work on a little growth and rehab. JMHO. -_-