The prominent Hollywood-fostered myths I wrote about were “hotness” — our unrealistic expectations regarding physical attractiveness — and “relationshipism” — the quest to be with another person without “exacting from the ego a price for being with other people.”

But there’s a third even more destructive and pervasive myth. It’s a myth we all fall for, even though we have ample reason to doubt the existence of this particular chimera. It’s probably the single biggest reason marriages fail and lovers part: happiness.

To most Americans, calling happiness a “destructive myth” sounds ridiculous — it’s the kind of thing that conjures up mental images of dour religious types dressed in black. After all, doesn’t the Declaration of Independence call the “pursuit of happiness” an “inalienable right” on par with life and liberty? Yes, it does. However, the right to pursue happiness isn’t the same thing as the right to be happy. What’s more, what Jefferson and company meant by “happiness” differs from our understanding of the word.

For us, the word “happiness” refers to a subjective emotional state more or less synonymous with “contentment,” with a dollop of euphoria thrown in for good measure. For instance, I spent the day after Thanksgiving with my family, many of whom had flown in from Puerto Rico for the occasion. We literally talked and laughed the day away. When I got home Friday night, I wished I could have bottled that day and made it last forever. That feeling is what we mean when we use the word “happiness.”

The problem is that these feelings are fleeting, not to mention subjective and even a bit egocentric. You can’t build an individual life, much less important institutions, around them. That’s why the Founders, harkening back to John Locke, St. Thomas Aquinas and, of course, Aristotle, understood happiness in more permanent (and more social) terms.

For Aristotle and those who followed him, happiness referred to “the quality of a whole human life — what makes it good as a whole, in spite of the fact that we are not having fun or a good time every minute of it.” Since our lives may contain “many pleasures, joys and successes” along with “many pains, griefs and troubles,” and can still be called “good,” happiness is neither increased nor diminished by our joys and sorrows.

While happiness requires things such as friendship, health, knowledge and, yes, material comforts, what matters most, according to Aristotle, is virtue. It’s virtue that enables us to make the right choices such as the “willingness to give up some immediate pleasures for the sake of obtaining a greater good later on.” As the philosopher Mortimer Adler, whom I’ve been quoting the past few paragraphs, wrote, the right pursuit of happiness consists in making the right choices. Make the wrong ones and while “we are likely to have some fun from day to day for a while,” in the long we will “ruin our lives.”

While Jefferson, Aristotle, et al., understood both happiness and its pursuit to be personal, our almost entirely subjective understanding of happiness would have been alien to them. Likewise, while they believed that happiness had a social and communal dimension, the idea that one person could determine whether we would be happy or not would have struck them as preposterous.

Nowhere is our flawed understanding of happiness more consistently on display than in the movies. Last summer’s “Before Sunset” picked up where the 1995 film “Before Sunrise” left off. In “Before Sunrise,” Joel (Ethan Hawke) an American, and Celine (Julie Delpy), a French student, spend 14 memorable hours together on an overnight train to Vienna. As they prepare to part, Joel, swept up in the moment, suggests that they meet again six months later there in Vienna.

“Before Sunset” picks up the story nine years later. Joel has written a critically acclaimed novel based on that night nine years ago. He’s in Paris on the last stop of his European book tour when he’s reunited with Celine. This time, they only have a few hours before Joel has to leave. We quickly learn that Joel did return to Vienna and that Celine would have but for the death of her grandmother. We also learn that Joel is married and has a son.

The getting re-acquainted and catching-up comes to a sudden stop with an outburst by Celine that reveals how much the failure to re-connect with Joel has effected her: a series of failed “relationships” that left her doubting if she’d ever know love. Celine wasn’t the only one hurt: Joel says that his marriage is an emotionally-barren sexless façade held together only by his love for his son. The film ends with them at Celine’s apartment. While doing an impression of Nina Simone, Celine seductively says to Joel “you’re going to miss your flight” to which he smiles and replies “I know.”

While “Before Sunset” is intellectually a cut above most movies, it still embraces the same destructive idea: happiness, both in love and life, is largely a matter of finding that one person with whom you share a special connection. Celine had become, as Joel said, an angry person, not because of some personal flaw but because she didn’t have Joel. Joel was unhappy, despite his professional success, not because his expectations were distorted but because Celine hadn’t come to Vienna. While we don’t know exactly what happens after the credits roll (there’s talk of a third film), we are certain that for Joel and Celine, the road to happiness leads away from their current lives and toward a future with each other.

“Before Sunset” may only be a movie but its expectations of love and life aren’t limited to the multiplex. Maggie Gallagher, the author of The Abolition of Marriage, among other books on the subject, has estimated that up to 80 percent of all divorces are unilateral decisions — that is, one party decides that she doesn’t want to be married to the other person anymore. (I used the feminine pronoun because the person doing the deciding is more likely to be the woman.) At that point, all that’s left for the usually dumbstruck other party to do is to secure the most equitable settlement possible concerning the division of property and custody. The law can’t or won’t compel the person who wants out to rescind or even reconsider her decision.

This right to end your marriage because you are unhappy, without giving a reason beyond your feelings — what we euphemistically call “no-fault divorce” — is what Gallagher meant by the “abolition of marriage.” (People have long had the legal and moral right to seek divorce for cause: adultery, abandonment, abuse and cruelty.) Gallagher notes that people seeking a divorce under “no-fault” circumstances often grant themselves what she calls a “retroactive annulment”: they claim to have had doubts about the marriage from its inception. They’ve concluded that telling the other person “I should have never married you” is preferable to saying “you don’t make me happy.”

They’re probably right. Given the subjective and fleeting nature of what we call “happiness,” basing something as important as love and marriage on its presence or absence seems foolish, not to mention selfish. (Okay, I did mention it.) Yet millions of Americans do, in large part because they’ve been taught to associate love and “happiness.” Like Joel, they go where they ought not to in pursuit of a feeling that, as sure as the sun rises and sets, will leave them all by their lonesome.