I think the Beatles were seriously out of balance after their India-'vacation'. I've forgotten where I've read it, but there's a theory that their stay in India could have caused a 'shift' in the band towards George. But Ringo had problems with the food, Paul kept writing songs instead of meditating, John stayed for the course but also kept composing new songs and after India dived into his affair with Yoko and other drugs of choice. I think George was already restless en searching after they stopped touring and when his songs were getting better and better it became more obvious that Lennon and McCartney weren't having their 'little brother' steal the show. So even mediocre Lennon and/or McCartney-ditties were getting more attention than very good songs by Harrison. I think it's a miracle that George attended the LiB-sessions at all and later even introduced Billy Preston which was a fine effort to lift the mood. Well, we wouldn't have that great "All Things Must Pass"-album without it!