The brain's "wanting" (dopamine) and "liking" (endorphins) systems are separate. Intense reinforcement of the wanting system can create a powerful craving for a person who no longer brings pleasure, explaining why people stay hung up on those who treat them badly or with whom there is no future.

When someone says they're turned off by 'nice guys,' it often means their nervous system equates the feeling of love with a fight-or-flight response. Consistency and safety feel boring because they don't trigger the familiar anxiety and chase dynamic learned from past relationships or childhood.

Research shows about half of adults experience "limerence"—an obsessive, emotionally volatile state of infatuation. The other half expects a calmer connection. Neuroscientist Tom Bellamy explains that these two "love tribes" have fundamentally mismatched expectations, which is a major source of heartache and dating disasters.

If your attachment system activates quickly, your ability to reason is compromised early in a relationship. The solution is to act like a drug addict facing their drug: use sober moments to create strict rules, limit contact, and aggressively scrutinize the person before your judgment is inevitably clouded by emotion.

Chaotic relationships are often mistaken for passion. They operate on a sympathetic nervous system level, driven by dopamine and cortisol. The 'highs' are just relief from anxiety, not genuine happiness. Healthy relationships are parasympathetic, fostering calm and safety through oxytocin and serotonin.

Most believe dopamine spikes with rewards. In reality, it continuously tracks the difference between your current and next expectation, even without a final outcome. This "temporal difference error" is the brain's core learning mechanism, mirroring algorithms in advanced AI, which constantly updates your behavior as you move through the world.

Human brain recordings reveal a seesaw relationship between dopamine and serotonin. Dopamine levels rise with positive events or anticipation, while serotonin falls. Conversely, serotonin—the signal for negative outcomes or "active waiting"—rises in response to adversity, while dopamine falls. This opponent dynamic is crucial for learning and motivation.

The brain needs a way to compare the value of disparate items like food, money, or social status. Dopamine serves as this common currency. It creates a standardized value signal, allowing the brain to make decisions and allocate effort across different domains by translating everything into a single, comparable scale.

The feeling of dissatisfaction after achieving a major goal is a feature, not a bug. The brain's dopamine system is designed to keep you moving forward. If any single achievement—a partner, a food, a drug—were permanently satisfying, the drive to live and procreate would cease. The system ensures you always have another place to go.