What will you do???

Here is a question for all of you that do not have teenagers yet. You think you are so smart, but just you wait... So last night, it is 11:00 pm. I am trying to sleep and my cell phone signals that I have a text message. Weird, I never get text messages. I look, and it is from Taylors girlfriend. Am I seeing things? I think I'm having a dream. As I read the first of three messages, She tells me that Taylor does not know she is texting me, but she would like to know if he can come to her house this weekend and attend her little brothers b-day party. As I lay there in a stupor, wondering what the hell is going on, I think back to when I was 15 and crushing on boys. All that I can recall is that I would have DIED before I ever asked a boys parents anything let alone even speak to them. What is happening? I think another woman is taking over MY son. I can't take it. So, I ignore the messages totally until I can talk to Taylor. The next morning I mention to him the text messages and he turned a slight color of green. He could not believe that she did it behind his back. I got the hint that he did not really want to go to this party, and just ignored the invite. Then she takes it in her own hands to get him there. I try to probe to see what he might do about it and he had no clue. I tried to explain to him that girls should be somewhat modest in their actions. Good God I feel old and it seems like my son has already turned into a typical man and lets his manhood be carried around in a purse. What to do?