Paul started dating Shevell in November 2007. She was a member of the board of the New York Metropolitan Transportation Authority as well as vice president of a family-owned transportation conglomerate that includes New England Motor Freight. She resigned from the MTA board in January 2012.

It was announced on 6 May 2011 that the two had become engaged. On 9 October 2011 Paul and Nancy were married at Old Marylebone Town Hall where his first wedding took place in 1969. The couple attended Yom Kippur synagogue services prior to the wedding, out of respect for Shevell’s Jewish faith, but did not seek a religious blessing for their union. Upon their marriage, Shevell became Lady McCartney.

Paul wrote the song “My Valentine”, from his 2012 album Kisses on the Bottom, about Shevell. She is a cousin of broadcast journalist Barbara Walters.