BREAKING UP IS HARD TO DO by NEIL SEDAKA, LENNY WELCH (and others)

"Breaking Up is Hard to Do" is Neil Sedaka's signature song,  

A young Neil Sedaka performs the original

Originally recorded in the early 60s and re-recorded in 1975 when he was suffering a fall in popularity. He dramatically slowed the song down to a ballad which assisted the resurgenge of his career (and was a distinct improvement in my humble opinion). 

However, 5 years earlier, US crooner Lenny Welch covered the song in a similar, relaxed version. Welch apparently approached Sedaka asking him if he had any songs that would suit his style of singing and Neil, after giving the matter some thought, re-wrote the song for him.

Lenny Welch with his original slower version

The song has also been covered by Little Eva, the Partridge Family and the Carpenters amongst others. 

David Cassidy and the Partridge Family

My favourite? It might surprise you, but I always thought David Cassidy had an excellent voice suited to the uptempo style of the song, so it's TPF from 1972 for me.