Don't forget Lennon was an art student. He may not have done stuff like Yoko's at that time, but artist progress & change. He was always someone who rebelled against something & Yoko help fit that bill & brought it out more. He was tired of being a Beatle and I think Yoko helped him break that and redefine himself in his eyes & the eyes of the world. I also think he used Yoko to say to the other Beatles, "I'm done being a Beatle, but am too scared to leave right now." It's all he knew in his whole adult life. Lennon wanted to leave before Yoko ever showed up. I read it was around Help!; mid 1965. He started to lay low leadership-wise & let whatever happened happen. Then he meets Yoko, they get together in 1968, and his leader personality comes roaring back on The White Album. That was his last try at it. In 1969, he was moving towards leaving & wasn't there as much creatively.