Complex sentence: This coincided with a prolific period in his songwriting and a growing desire to assert his independence from the Beatles, tensions among whom surfaced again in January 1969, during the filming of rehearsals at Twickenham Studios for what became the album "Let It Be".
Split into simpler sentences: This coincided with a prolific period in his songwriting and a growing desire to assert his independence from the band. Tensions among the Beatles surfaced again in January 1969, during the filming of rehearsals at Twickenham Studios for what became the album "Let It Be".