My son is heading to college in the fall, and he's behaving worse than ever. I finally understand why.

The writer's son is college-bound, but he's acting out this summer. He seems to be pulling away and only wants to hang out with friends.

• My son is heading off to college in a few weeks, and he's been acting out this summer.
• I learned that he is "soiling the nest" so that it's easier for him to leave home.
• I understand that my relationship with him is evolving, but it still hurts.

It's been the joy and honor of my life to raise my son. He's an only child and has always been sweet and respectful; I've been thrilled to watch him progress toward adulthood. But that progress is now coming at warp speed, and at times, it's proving to be a sticky transition.

May's high school graduation was an incredibly proud moment. After the parties and celebrations, I'm now in full-up prep mode. Our kid is heading off to a university nearly 2,000 miles from home in a few short weeks. There are many things to consider and stay on top of, like firming up financial aid, dorm room assignments, and course registrations.

As I busy myself with logistics, it's clear my kid is already gone — on some level. And while he's not outright hostile or disrespectful, tensions have certainly risen a bit.

His behavior has changed this summer

My son rather be in his room (door closed, of course), with his friends, or off doing his own thing. God forbid I ask him where he's going, who he'll be with, or when he'll be home. He usually slinks away if I try to go in for a quick hug.

The typical response? "Geez, Mom. Lay off! Leave me be!"

He recently turned 18 and is considered a legal adult. So, many of the household rules we had in place just a few short weeks ago now seem to have fallen by the wayside.

Technically, he doesn't need permission to do most things anymore and can make his own calls. Thankfully, so far, they've been good ones.

Our relationship, which up until now has been quite close, is shifting, too. I know this breakaway is a normal, healthy part of the parenting process, but it still stings. He's testing the waters, trying independence out for size. He's not supposed to stay with us forever, after all.

But I'll be honest; it hurts a bit. So, what gives here?

He's 'soiling the nest'

After doing some research, I learned that sudden sullenness is a common phenomenon as children prepare to move out. Experts call it "soiling the nest." While parents are anxious about an empty house, kids are also trying to figure out how to fly away. It's easier for them emotionally to act out and detach before the big farewell. Subconsciously, they want to make us so uncomfortable that everyone's relieved when we show them the door. It makes sense, I suppose.

My son isn't just getting ready to say goodbye to his dad and me. He also has his good friends and his girlfriend to consider. They are all headed to different schools across the country, and I know he's trying to figure out how to maintain those relationships. While I understand this, it doesn't mean I'm not a little jealous that he's spending most of his free time with them instead of me.

A new city, new school, new friends, new home. It's a lot to wrap a teenage brain around. I understand that soiling the nest is a coping mechanism, albeit a frustrating one.

Our relationship is changing, not ending

Of course, our son doesn't need me or his dad in the same ways as he did when he was younger. But he still needs our support. That means trying to understand and accept sometimes challenging behaviors as he prepares for this next important step. That includes one-word mumbles, occasional outbursts, and increasingly infrequent time spent with his parents.

I want him to be happy to pack his bags and excited, not miserable, to leave home behind. If putting a little distance between us right now makes it easier for him, so be it.

I'm grateful this summer gave me a peek at what it might be like when my college student comes home for visits. He'll want to come and go as he pleases, like any adult does. He likely won't want to answer to us. I might not know if he's joining us for dinner any night. And that's OK. We will always welcome him back with open arms, even if he's stinking the place up a little while on the way out.