well, its hard to tell but in a paul mccartney biography sinabi that the reason why stu left was because he and paul hated each other. i dont think they liked each other that much because stu was one of john lennons art school mga kaibigan so paul might have felt a bit left out maybe.
No they didnt get along. Now paul originally liked playing base but when Stu left the band he kinda forced paul to take his place on base. But the worst part is, stu left the band to marry Paul's ex girlfriend, Jane Asher, that isn't good is it?
It is a common misconception that he left to marry Jane Asher. In 1962 the Beatles hadn't even met Jane Asher. He left because he didn't feel that the Beatles were going to keep him longer anyway, due to the fact that he was a horrible bassist. Also, the girl he left to marry was Astrid Kirchherr, not Jane Asher. Astrid was a photographer they met in Hamburg during their sessions at the Kaisercaller