When John Lennon and Yoko Ono first met they knew from the beginning that it was meant to be. Although, if you read "some" book about their relationship, it is made out to seem like Yoko hunted him down and forced him to see her. Personally, I don't think that was the case. I think that John really loved her from the start. People did not like the fact that John was with Yoko. And that includes the other Beatles as well.
You also have to remember that John started acting differently during this time. There was the "Bed-In" for peace. John truly believed that these kinds of actions would help world Peace. A lot of people thought that this was non-sense and thought of John and Yoko as quite goofy actually. John realized this but continued to act out in this way. He is quoted here as saying if he has to be The Abbot and Costello of his time he will be. He truly believed that these things would at least help World Peace. Maybe they did, maybe they didn't. The other Beatles were growing tired of the antics of John and Yoko.
John had chose Yoko to remain at his side no matter what. And that made thins a little uneasy for the rest of the group. He was starting to perform on his own, record on his own, and doing just about anything with him and Yoko. He actually started to be known for his antics. There was an interview with Paul McCartney once when he said John had been on "trip" and thought he was Jesus Christ himself! Wanted this to be put out in the press because he truly believed it. And yet, Yoko remained right by his side. That says quite a lot. John and Yoko had their own agenda, and the rest of the fab four was not going to be part of it. AS john stated in one of his interviews, "I started the fucking group, so I disbanded it also!" Johns love for Yoko could not be stopped. Not by family, friends, or fans. He was thoroughly in love.