Since you never once mentioned the title of the movie you are referring to I am assuming that you are talking about Rene Russo's performance in A Thomas Crown Affair. The chemistry between Pierce Brosnan and Rene Russo, IMHO, greatly surpasses what little attraction I perceived between the ancient Sean Connery and Catherine Zeta-Jones. Rene Russo exuded sexuality through the very maturity that has she has been previously knocked for. Her sexuality stems not only from her physical appearance but her mental capabilities. I was not at all impressed with the 'depth' of Zeta-Jones' character and I found Connery to be utterly repulsive. Now there is an example of a bad choice in sex symbols. The man is old, he's gotten chunky and the character he played was a complete jerk!
As for the notion that the leading lady should be significantly younger than the leading man, that's absolute nonsense! Sean Connery was disgustingly older than Jones. Relationships like these promote the idea of the 'helpless woman' who needs a 'stronger older man' to take care of her. That's crap. And the whole idea that a woman cannot be sexy after a certain age is ridiculous while someone like Sean Connery is still seen as a sex symbol!!