The Valentine Industrial Complex would like us to believe that there are only three words that matter on February 14. But if you’re looking for a way to deepen not just your relationship with your beloved but your own sense of happiness that you’re paired off with them, you could scale that back to just two: Thank You.

It’s one of life’s great ironies that the people we love and rely on the most tend to be the people we to whom we express gratitude least frequently. I blame it on efficiency: we would never get out the door for work in the morning if we actually took the time to express our thanks to our partners for all the millions of small, specific ways they help us. “Thanks for feeding the kids this morning/buying toothpaste last week/putting me on your company health insurance/helping cover the rent/talking me into this blouse instead of that ill-fitting purple one I almost bought instead” may be a good start when it comes to cataloging your reasons for gratitude each morning, but you’re never going to catch the bus that way.

So most of us just file that stuff away as “Implied and Understood Between All Parties” and leave it at that. It’s one of the nicest things about being in a stable relationship; the ability to take for granted. It’s evidence of a gratifying level of trust and comfort between two people when you don’t feel compelled to thank each other every day, all day.

But once in a while – say, mid-February, just for kicks – it’s not a bad idea to step back and remind yourself and your partner exactly why they matter to you. To call out all the important ways they have helped, shaped, or inspired you.

First of all, a thank-you letter will stand out in a sea of pink and red cards, so many of which seem to fit uncomfortably over our deep emotions like frilly lace gloves left over from Madonna’s Like a Virgin period. It’s unexpected. And a thank-you letter is specific to its recipient in a way that no Valentine’s card, purpose-built to appeal to anyone who blazes through the stationery aisle at the drugstore late in the evening on February 13^th, ever could be.

Second, a thank-you letter can deepen the relationship its writer shares with the recipient. In a 2010 study from the International Association of Relationship Research led by Sara B. Algoe of the University of North Carolina on the relationship between gratitude, indebtedness, and romantic relationships, researchers concluded that an expression of gratitude “was associated with increased relationship quality for both members of the couple. . .The little things may make a big difference within the daily lives of individuals in romantic relationships. Gratitude may help to turn ‘ordinary’ moments into opportunities for relationship growth, even in the context of already close, communal relations.”

In other words, an expression of gratitude in a relationship that is moribund can create the kind of spark that Hallmark writers dream of. And even people in healthy, loving relationships, the kind that makes you simultaneously jealous and nauseous on February 14^th, can benefit.

Finally, the process of writing a thank-you letter makes us practice seeing our partners’ positive traits. To know what to include on the page, we must necessarily spend some time sifting through the (hopefully many and varied) positive contributions to our lives. Just pondering those things, even if we never write them down, helps reinforce what scientists term “positive recall bias”, our ability to notice the good things instead of, or at least before, the negative things. If gratitude were a muscle, writing a Valentine’s Day thank-you note would count as an excellent workout.

For maximum effect, I very much recommend you keep a copy of any thank-you note you write your beloved and store it in an easily accessible spot. That letter will come in handy on, let’s say, the day in June or October that you walk into the bedroom and notice a week’s work of dirty socks and t-shirts piled vertically atop the closed lid of the hamper, while within the hamper, the air sits empty and undisturbed and shy of its dream of preventing exactly the eyesore taking place overhead. I don’t care how much I love you (in that purely hypothetical scenario, of course). I’m going to struggle with that visual.

Rather than scream, a quick scan of a copy of letter I keep in my nightstand drawer reminds me that the vertical laundry stacker in question also unclogs our children’s long hair from the bathroom drains because he knows I can’t do that without dry heaving. He may not care so much about dirty socks, but he is kind to my elderly mother and her sister, he is a devoted dad, and he can make me laugh with a mere raise of his eyebrow, no matter how grim my mood. As I reread, the laundry hamper situation fades into the periphery.

So for a Valentine’s sentiment with impact far more enduring than a box of chocolates or a vase of roses, pull out a blank piece of paper and start writing down the reasons for your two little words.

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