Not talking about double entendres but ones that have the whole being misunderstood. My prime candidate is "How Long (Has This Been Going On)" by Ace. It's not a romantic break-up song though it works well as one--it's about a band-member being poached: http://en.wikipedia.org/wiki/How_Long%3F
I like it a lot so I'm posting it twice, one from '77, one more contemporary though both by the author.
http://www.youtube.com/watch?v=qYRmQRtS3cw << from Strat Pack--Fender 50th B'day Celebration An outstanding concert