nah it's because to Ned, when his pops and brother was getting murdered by the mad king Jaime was chilling doing his "duty" it wasn't until the war was done and tywin came tru kl that Jaime stab the mad king in the back and was sitting on the throne like nikka we made it, Jaime was content with being viewed as the kingslayer
The order of torching the city with wildfire was the last straw, aerys fukking thought he's gonna turn into a dragon thanks to that. Jamie put an end to that, breaking an oath but saving lives