I think it depends.

My mom and I were talking about something like this yesterday. I've decided that I wouldn't be happy dating someone who is exceptionally older than me. My mom's boyfriend is ten years older than her. The average lifespan of a man is 70. So he may have only 20 years left. A woman's average is 80. So my mom has 40 years left! She has atleast twice as many years left than him! Even if he succeeds the average (which alot of men do), it would still make me sad to think about it.