Dear husband,

There's not much out there that fulfills me more than watching our tiny humans develop and grow into themselves. I love being their mom. But watching you be a dadthe best dad in the world— helping to guide them and shape them into the adults they will one day become? That's the sweet cherry on top of it all, my love.

My transformation to 'mother' has cracked my heart open and then pulled every ounce of vulnerability that I have out of it; every bit of love, every bit of passion. It has helped me become a better, happier, more tired version of the woman you married.

Related: To my husband: When motherhood gets tough, you make it easier

But as beautifully life-affirming as it has been for me to assume the role of 'mom'—to take on all that that word means: the magic, the exhaustion, the fun, the frustrations—it has been equally life-affirming to see you assume the role of 'father' to our children so naturally, so happily.

While there are certainly many challenging aspects of being someone's parent, you seem to find joy anywhere you can in fatherhood; honor in being our children's role models; pride in raising a family with me.

And I'm lucky to be alongside you on this journey for so many reasons.

I love seeing you play together.

You do the things my heart is too fragile for, my nerves too fried. You flip them upside down, throw them (so!) high in the air, and put them on your shoulders so they can feel like they're on top of the world.

You are the best dance party host, hands down. I haven't seen some of the moves you bust out when "Can't Stop the Feeling" comes on since college, but I'll tell you what—I'm glad they're back.

I love hearing you teach them about things.

You know many interesting facts that I don't have space in my brain for because it's too full of an eclectic (and dare I say useless) combination of every single pop/rap/r&b song produced in the '90s-'00s. (The majority of which I cannot teach our children.)

You teach them things like what the difference is between a lake and a pond or which dinosaur is which. You tell them all about the history of the Celtics and why the sun sets when it does. You look at the stars with them through the telescope you bought and talk about the planets in outer space. You have the thoughtful answers to all their why's.

I love watching you watch them with wonder.

Like when our oldest had her first dance recital and she bravely went on stage without fear—I watched you watch her in awe. Or the times when I notice that twinkle in your eyes as they tell you a story. You'll nod and say "mmhmm" and they'll use their hands enthusiastically, chatting away—both parties totally engrossed in each other.

Related: It’s science: Affection is the key to building a strong father & son bond

Or how you'll laugh when they dig up a worm in the garden you built together or touch the fish you guys caught without giving it a second thought. The smile they put on your face is worth it all.

I love eavesdropping when you talk with them.

I can always count on a "So, how was your day, Dad?" to put a smile on my face around 6:30 pm every night. I know I'll hear something like, "What kind of dance do you think a cha-cha is?" when you're reading about Gerald in Giraffes Can't Dance.

Listening to who you all choose to pray for when you're getting them ready for bed or hearing you encourage them with a simple, "You are so brave! Look at you go!" fills me with more happiness than I could ever accurately explain.

Related: It’s science: This is what happens to a dad’s brain when he has a daughter

I suspect I'll feel the same way when you're walking one of them down the aisle.

Or as I watch you watch them, beaming with pride as we snap pictures at graduation.

Or when you're holding their child for the first time, with tears in your eyes, no doubt.

I'm so happy watching you be happy.

I'm so happy you're my partner.

I'm so happy you step up to the plate time and time again. Day after day.

I'm so happy you love being a dad.

You're no longer just the man I fell in love with all those years ago. You are no longer just my husband. You are now, also, the father of my children. I'm so proud of you, and I'm proud of what we're building together every day.

And I suspect I'll feel that way for the rest of my life.

A version of this post was published June 4, 2018. It has been updated.