Frank Sinatra met Mia Farrow in 1964, when she was filming Peyton Place at 20th Century Fox. The media found out about them when Frank took Mia and some of his other friends on a yacht cruise. Many made fun of the age difference between the couple, as he was 30 years older than her! They married in 1965. Frank referred to her as his "child bride" and sang "September Song" to her. In 1967, they divorced shortly before she went to meditate with Maharishi Mahesh Yogi in India (which the Beatles, Donovan, Mike Love, and her sister Prudence of "Dear Prudence" also did).
Though they weren't together long, their relationship was quite publicized because of their combined fame and age difference controversy. I think they are absolutely classy together!