Girlfriend Rules Enforced!!!

So...we thought we were getting it under wraps when we limited the texting and the phone time to an hour a day. In a way, I think it made it just a little bit worse.
My girlfriend and her 4 boys, my godchildren, came over on Saturday. Just a little BBQ and some Apples to Apples....BTW, if you do not own this game, go out and buy it. You will have a great laugh.
Since people were over, Nathaniel decided to ask if his girlfriend could come over as well. No biggie. However, they seemed a bit too clinging. A few times I literally told him to remove his hands from her. Nothing that bad, just too close for my comfort.
All the kids went to the park, took skateboards etc...And low and behold, we didn't find out until this am...His skateboard is gone. Vanished, no where to be seen. Mind you, this is his prize possession. He loves this long board. He better for $300.00.
turn out, Sage gave it to him to carry home. He was too engrossed in his girlfriend that he gave it to his god brother to bring home. It came home, never made it in the house. Someone got sidetracked...No one realized until this am when he went to go get it to ride. And it is gone.
He was devastated and wanted to blame everyone but himself. I think heknew he should have been a bit more responsible with something he loved...But he was too busy walking his girlfriend inside and thinking someone else would take care of it.
So, we now have limited the time he has with her. She is a good girl, but he is just too involved at his point in his life, All he can focus on is her. And I'm just not ready for him to give up living his life and enjoying it to its fullest potential.
I'm sad, angry, upset and bummed out. It is hard to implement these types of rules. At the same time that I blame him for the skateboard, I am torn because I feel so utterly bad for his loss. Motherhood is rough!