Yoko was also resented because of her presence in the studio actually telling the other Beatles what they should be doing musically. That was when a lot of it really started.
and some have speculated John and Yoko might have divorced if he had continued to live. We just don't know there. Basically, both women got it worse then any of the other Beatles wives. Linda got called ugly just like Yoko, made fun of for her body hair, her house broken into and her photographs maliciously stolen and destroyed (carol bedford confessed to that in the Book Waiting for the Beatles).
Someone earlier in the thread tried to dismiss the fans as loving Linda because she was blond. There is nothing further from the truth. They used to shout insults at her through the windows while Paul was at the studio.
Linda was changing Paul just as Yoko was changing John. As the band was collapsing, Linda was showing Paul a dosmestic life (soemthing she really didn't have either) as an alternative. Just because it doesn't have the flash of the art world that Yoko brought John, doesn't mean it was any less deeper. For Paul, it was a brand new way of living. (He had already done the avante garde stuff anyway)