Aerys and Tywin friendship started A Song of Ice and Fire [Spoilers EXTENDED]

[Spoilers EXTENDED] For me in the world of Westeros there is a dividing factor, the time before the friendship of Tywin Lannister, Aerys Targaryen and Steffon Baratheon and the time after, think about it everything is set in motion by their friendship as Tywin is put as hand and is a good hand Aerys starts to act resentful to Tywin which results in him not trusting him and starting to insult him, not letting Rhaegar marrying Cersei is what later causes Steffon death and Varys going to court, besides the Defiance of Duskendale would probably never happened as Aerys wasn’t planing on going to Duskendale before Tywin said it was a bad idea to go resulting in him not being so paranoid and mad, and if it’s true that Harrenhall was Rhaegar trying to make a great council due to Aerys madness it wouldn’t happened as Aerys wasn’t that mad and paranoid (so in my mind) probably what set all of the events that resulted in A Song of Ice and Fire all happened because a young Tywin become friends with a young Aerys