If you're a 35 year old businessman, chances are you won't find many 25 year olds who will want to date you. A 35 year old actor will have 25 year old women who like him because he's famous, rich and doesn't seem like a pervert in the media. And when a 35 year old guy dates a 25 year old woman, that relationship has a lower chance to work out than a 35&33 year old couple.