This Christmas is the last one before my son goes off to college. I'm already grieving his absence.

• This is the last Christmas my son will celebrate while living in our home.
• As I go through the holiday season, I can't stop thinking about him as a young boy on Christmas. 
• I'm pre-grieving his absence but trying to remain festive.

In my house, there are rumblings of seismic life adjustments coming along with this year's holiday traditions. As a result, I don't feel altogether festive.

My only child heads off to college next fall. He's been tremendously busy submitting essays and getting his portfolio prepped. Applications are going out, acceptances are starting to come in, and, in the middle of it all, he's trying to carve out much-deserved downtime with his friends.

We are extremely proud of him, but I know all his hard work means this is the last holiday he'll spend with me and my husband as a full-time member of the house he's called home since he was born. He'll be flying away in a matter of months to a university that's yet to be determined.

Suffice it to say, I won't have to watch "It's a Wonderful Life" this month to feel emotional.

I can't stop thinking of the past 17 Christmases we spent together as a family

When I put up our holiday decorations this year, I remembered all the baseball cards, Lego Minifigures, "Star Wars" treats, and other silly trinkets we stuffed into his stocking over the past 17 years.

I gravitated toward the baubles he's made through the years and gave them prime placement on the tree: the fingerprint ornaments, the clothespins reindeer, the glass globes he brushed with paint as a preschooler and carefully dusted with glitter when his hands still had dimples.

As far as the cookies go, it's been several years since he's helped with the prep or baking — he's been too busy hanging out with his girlfriend and his buddies, going to the movies, or studying. But you better believe I'll make giant batches of his favorites this year. I'm sure he'll plow through them haphazardly, in that way teenage boys do, while prepping for his winter finals. I'll be the one to remember to leave a symbolic few out for Santa on December 24.

His grand breakaway has begun, and I'm really feeling it right now.

I'm starting to grieve his absence

I love the holidays. It's a time of feasting, feting, and being with family, as well as cherished friends who have become family. But amid the revelry, I find myself left with a strange kind of pre-grief. Legally speaking, this is the last December he'll be with us as a child, a dependent, and a permanent resident of our home.

Don't get me wrong: It's wonderful to watch as he grows into a young man, and it's been the privilege of my life to help raise him. I've always known this is part of the parenting deal, of course. But this time of year, and this time of transition, makes me miss the younger version of my son.

I'm trying to give myself a little grace. Like death, divorce, or job loss, a child leaving your home is earth-shattering. It has real-life impacts, and I'm not the only one feeling them. Dear friends who are already empty nesters have kindly confirmed that the senior-year holiday season was especially rough.

I'm still trying to remain festive

While imagining life without my son under our roof is difficult during this period of good cheer, I'm doing my best to leave room for excitement.

As the pieces of what will become his adult life start to come together and into focus, I'm aware he'll come home, and he'll be back with us next December. While our family dynamic will be different in ways I'm still trying to envision, its bonds will always remain.

That's the biggest gift I could ask for this holiday.