Age disparity in relationships

just to have an idea, in your opinion 17 years of difference are too many, of course man older than woman. Can you guess who is the name? Well this man likes so much this beautiful blonde girl as she is very smart and pretty, but he's a bit afraid to be a bit too much old to stay with her, can you imagine when he will turn to 50 she will be only 33, I mean a bit strange you know, But this man cannot hide his feeling for this beautiful Russian girl, maybe he should live at the present without to be worried what's going to happen in 10 or more years, at the end we live this time all the rest is in our mind.
What in your opinion the maximum difference in age in a sexual relationship, I found this article on wikipedia quite interesting, basically it says the age of the woman should be greater than the half of the man plus 7, i.e. let's say the man is 38, the woman should be at least 26 (38/2 + 7).
Someone says age doesn't mind in love but I guess there are some limits, otherwise you run the risk to be ridiculous. Poor this man, the older the more he likes younger girls.