Equanimous Equilibrium

Why are breakups so hard? I understand it's good evolutionary practice to keep relationships stable enough to take care of the kids, but why is it so hard to move on even after that's done? Investment in memories. I'm a nostalgic type of guy. I will remember the good times disproportionately. I have trouble recalling the pain, annoyance, bickering, playing games. I wish I can cue my emotions up at will so I can remember to care for someone when I'm taking them for granted and to take them for granted when I no longer have their affection. It's silly how my emotional feedback circuits are so implacable, but I guess equilibrium is based on that bouncing back and forth. Is there such a thing as equanimous equilibrium? A balance that is held not by violent reaction but by sober resolution?

Yes. It is accessed by having a clear intention and thoroughly following through with it, plugging daily results into a conscious feedback mechanism rather than the unconscious one of habitual emotions. If I am ever to get anywhere in life, I must decide and do rather than deliberate, dwell, and allow chance to run my life for me. This is hard, but it's harder to live and die a slave to circumstance and stupidity.