N.M.
Hi C.,
Can I offer you a little advice not as a mom but as a son whose mom used to "get involved" in my dating life?
Don't.
Be supportive as I'm sure you are. Be there to talk when he wants to. Have the birds and the bees talk if you haven't already. It does help just to know you care.
But other than on his terms....let it be. He'll get hurt, as it sounds like he has already to some degree. But with every hurt, he'll learn a little more about life and love. And yes it's probably hard to watch as a mom or dad....but I know I would not have been ready to marry and love the incredible woman that I ended up with if it hadn't been for all the "loved and lost" relationships that came before her.
It will happen for him. But he is still very young. Let him live his own life in this...just like I had to....and you had too. Just that fact that you are there and trying to help him means he has all the support he'll ever need in this.
Hope this helps ease your mind even a little.