Shawn had gained a little weight, but Samantha found him more attrac-
tive than ever. Shawn thought Samantha looked better than ever, too. Even
though he appreciated how great she looked dressed up, he confided to his
friends that nothing was sexier to him than when she woke up with tangled
hair and no makeup, wearing one of his old T-shirts from college. Lately
they kept their voices low to steal a few extra minutes while the baby slept,
because the morning, alone and unguarded, was a rare moment when they
could enjoy the presence of each other.
Samantha had learned how to help Shawn overcome the insecurities
that held him back at work, and he found ways to free up time for her, so
she could pursue her master’s degree. But more and more they just savored
each other’s company. Sometimes they didn’t talk at all, and while once that
would have seemed strange to them, these days it just felt right. Samantha
remembered the night Shawn reached for her, stroked her hip, then took back
his hand. She heard him flip over and make the sound he always made just
before going to sleep.
“What’s wrong?” she asked.
“Nothing,” said Shawn. “Just making sure you’re there.”
Dopamine got the nickname “the pleasure molecule” based on exper-
iments with addictive drugs. The drugs lit up dopamine circuits and
test participants experienced euphoria. It seemed simple until studies
done with natural rewards—food, for example—found that only unex-
pected rewards triggered dopamine release. Dopamine responded not
to reward, but to reward prediction error: the actual reward minus the
expected reward. That’s why falling in love doesn’t last forever. When
we fall in love, we look to a future made perfect by the presence of our
beloved. It’s a future built on a fevered imagination that falls to pieces
when reality reasserts itself twelve to eighteen months later. Then what?
In many cases it’s over. The relationship comes to an end, and the search
for a dopaminergic thrill begins all over again. Alternatively, the pas-
sionate love can be transformed into something more enduring. It can
become companionate love, which may not thrill the way dopamine