The song "Bridge over Troubled Water" made Simon and Garfunkel then slowly unmade them. It was a huge hit that helped cause a lifelong rift between the two. It seems Paul Simon regretted letting Art Garfunkel sing the lead vocals and resented all the attention he got for it. Things escalated from there. And the childhood friends drifted apart, their isolation from one another fathoms deep.  The song soars beyond anything so petty and earthbound. And would not have been the same if anyone else sang it. What strange complicated beings we are. Planting poisonous seeds that grew such beautiful things.

https://www.youtube.com/watch?v=4G-YQA_bsOU