John Lennon and Paul McCartney formed an iconic song-writing partnership as members of The Beatles, with their work credited jointly as Lennon-McCartney. Despite their creative synergy, tensions arose in the late 1960s due to creative differences and the presence of Yoko Ono in the studio. The band officially split in 1970, with Paul McCartney announcing his departure and filing a lawsuit to dissolve the band's contractual agreement. The feud between Lennon and McCartney culminated in a series of pointed songs exchanged between them, but they eventually reconciled before Lennon's tragic death in 1980. McCartney paid tribute to Lennon with the song "Here Today," reflecting on their complex relationship.
Source: https://www.liverpoolecho.co.uk/news/liverpool-news/beatles-paul-mccartney-reduced-tears-31709658