Somewhere between the joy of happily ever after and the sting of a broken heart lies the majority of our relationships — temporary affairs full of happiness and pain, of promise and remorse, which we blindly hope leave us just a little better and wiser. It’s here, in this middle ground, where so many hearts reside, accepting love as the sometimes triumphant, sometimes devastating, but always essential pursuit of our lives.

Cinema, though, has always been slow to catch on. We live in the age of the meet-cute, of movies that aren’t so much about love but the quest for love or the loss of love. As a result, the idea of love itself, and the bittersweet role it plays in our lives, is one that’s rarely been fully explored.

Woody Allen managed to do it with both “Annie Hall” and “Manhattan,” finding something tragically beautiful — and deeply resonant — in these stories about the wrong loves at the wrong time. A few years ago, screenwriter Charlie Kaufman did much the same with “Eternal Sunshine of the Spotless Mind,” casting the repetitive follies of love as an inevitable cycle of our lives.

And now here is Jeff Lipsky’s captivating “Flannel Pajamas,” an observational drama that cuts through to the truth of love and loss with confidence and patience. Turning its back on the sentimental for the universal, this isn’t a pick-me-up tale of how we wish life was, but a loving embrace of a movie made by filmmakers who know a thing or two about how it actually is.

It starts on a blind date. Stuart (Justin Kirk) and Nicole (Julianne Nicholson) were introduced by friends, and as dinner quickly turns into dessert and then a cab ride home together, all seems right with the world. But as this date turns into a long-term relationship, tensions slowly start to surface. What’s clear from the outset is that Mr. Lipsky, who also wrote the screenplay, is less interested in creating a conventional romance than in deconstructing the ways such superficial stories minimize and simplify their subjects.

Mr. Lipsky doesn’t force us to like these characters, nor necessarily this couple, but instead develops the full arc of a relationship — the good, the bad, and the ugly. At times, it looks immaculate, as the pair embrace their newfound intimacy, see each other through their fears and insecurities, and finally decide to move in together.

At other times, though, all we can notice are the cracks forming in the surface. From the very first night, Nicole’s best friend doesn’t care much for Stuart. Later, as Stuart heads home for the holidays with Nicole, he doesn’t seem to like her family. Nicole wants children, but is willing to defer to Stuart to wait a few years. Stuart, who makes far more money than Nicole, wants to take care of her and repays her college loans.

As the weeks drift into years, as cohabitation graduates into marriage, and as the honeymoon lurches forward into the constancy of married life, we see those initial pebbles of conflict snowball into deadly boulders of resentment. Stuart comes to hate Nichole’s family and her best friend, and Nicole hates him for it. Stuart wants to play the role of protector and provider, but Nicole wants to stand on her own two feet, starting her own catering business and seeking her own success. Stuart’s aversion to children and Nicole’s obsession with having them remain unchanged.

What’s powerful about “Flannel Pajamas” is that these two remind of us of flawed couples we know — personalities of people who fit together, but not perfectly. Like trying to force a puzzle piece into a spot it doesn’t fit, Stuart and Nicole function if they push as hard as they can to make their relationship work, but without the added effort, they will never be what the other needs. And yet they try, committed to building something that’s more good than bad, believing that affection is enough to overcome the obstacles of family, friends, dreams, and emotions.

Amid this struggle, “Flannel Pajamas” becomes one of the few movie romances to own up to the truth: In the end, marriage is about a whole lot more than just love.

What’s magical about the movie, and what may just set it apart as a breakthrough for audiences fed up with the stereotypical formulas regularly flooding the multiplex, is that Mr. Lipsky lets us observe, criticize, and discern without ever telling us what to think of Stuart and Nicole. We peer in on a couple at the most important moments of their relationship and contemplate just what about them is right and wrong, pure and flawed. It’s one of those rare films that truly respect its characters without forcing them into a cliché or a situation that seems unwarranted or out of place. Really, they are as smart as we are, just as aware of their relationship’s flaws, and nothing occurs in the film’s second half that didn’t start in some subtle way earlier.

For their parts, Mr. Kirk and Ms. Nicholson deserve equal acclaim. They disappear into these parts completely and by film’s end, we are not judging performances but real personalities whom we have come to love, hate, and empathize with. Mr. Kirk’s Stuart is arrogant and self-absorbed but also well-meaning, his love appearing in cycles as he copes with his career — a fact that Nicole recognizes. Ms. Nicholson’s Nicole is captivating, her freckles, frankness, and fear forming the image of a real woman under real stress, trying desperately to do the right thing.

It’s the ending of “Flannel Pajamas” that epitomizes Mr. Lipsky’s love for his flawed couple. In almost the blink of an eye, he reminds us without melodrama of how comfortable, exciting, and lonely love can be, how a romance leaves an imprint on a heart forever. And just as anyone would consult a best friend through heartache, Mr. Lipsky hugs his two lovers close. They’ve enjoyed the laughs and endured the tears, and now all their creator wants for them is to find some sort of peace with themselves and where they’ve been.