Perception, memory, and behavior are each dependent upon your current state of mind, which in turn is dependent on local conditions.
Memory is state dependent - that is, memories formed during happy states are better remember when happy, memories formed when sad are better remembered when sad. When a loved one does something irritating it seems they are always doing such things; memories of earlier endearing actions are hard to access.
This is not only true for anger and affection - each trance produces characteristic perceptual biases that favor processing information consistent with the current trance. The mood disorders, depression and anxiety are recursive trances, and so persist and even feed on themselves.
"You don't throw a whole life away just 'cause it's banged up a little"
Tom Smith in "Seabiscuit"
