My take (partly influenced by watching The Crown series) was that both were brats who never grew out of adolescence into adulthood and both loved being the center of attention.
Their marital clashes, including infidelities, revolved around this basic fact.
A lot of BS in The Crown, especially the episodes dealing with Thatcher.
As a Freeper, I post with some trepidation that the very mention of the Crown is forbidden simply because it is in opposition to the Anti Netflix Free Republic Dogma