I totally understand your reaction. But I don’t agree that you did the right thing. Drawing a line in the sand with teens never ends well. The kid just digs in. She doesn’t understand your concern and thinks that her “love” for the boyfriend is more important than him doing something risky and stupid.
There is an important distinction between punishment and teaching. Punishment stops something, but the kid being punished doesn’t learn much. In fact, they often learn the wrong lesson. Teens often “learn” that the best way to try out new things is to do them under their parents’ radar. It encourages sneaking around. Teaching, however, helps a teen learn how to make better judgments for herself.
We both know that this relationship is probably not going to be the best one or the last one. The teen years are an important time of discovery. She needs to see for herself that what someone does matters. Right now, all she is able to see is that you are blocking her from seeing who she thinks is the love of her life.
You can change course without violating your values. Take a deep breath. This is an important teaching opportunity.
Now that the dust has settled some, offer to talk — as calmly as you can — to them both. Ask what he was thinking in posting what he did. He probably wasn’t thinking. He probably was being impulsive and stupid. He might even regret it if you can give him a way to acknowledge as much without giving up all of his pride.
You have the right and responsibility to voice your worry that his lack of judgment might show that your daughter isn’t safe with him. Give him room to apologize – or not. Then give your daughter room to talk about why she thinks what he did is okay. Chances are you’ll hear something like that “everybody does it so what’s the big deal” in which case you can do a little educating about why it really is a big deal. (It speaks to lack of self-respect for himself and your daughter. It speaks to a difference in values you find worrisome. What goes on the internet stays on the internet. Those are just a few reasons for a parent like yourself to be upset.)<
Then give your daughter room to make her own decision. It’s the discussion, not the original posting, that is going to show her more about what kind of person she is dating. Just maybe, the young man will have learned an important lesson and will turn out to be an okay enough boyfriend for you to tolerate. Just maybe they will both learn more about being respectful of each other and careful about what they decide to post on social media.
Do give your daughter a vote of confidence to make right decisions — even hard ones. You probably didn’t raise an idiot. Given room, she’ll eventually figure out what kind of person she wants to make a life with.
This is hard stuff, I know. Do consider that what you do about this situation sets in motion how you and your daughter will deal with other problems as you all go through the teen years.
I wish you well.