The couple started dating in 2007 and got married in 2011.
"It can be quite hard to say 'I love you' to someone. I felt this with Nancy, but to say it wasn't that easy," thesun.co.uk quoted McCartney as saying.
The former member of popular band The Beatles, has expressed his feeling in a track, which is part of his new album "New".
--IANS (Posted on 11-10-2013)