My daughter got a boyfriend from social dating tours.

For weeks, I have noticed that my daughter is spending a lot of time in her room. She seldom goes out. I thought she was just busy with her school papers but I found out she was busy communicating with this boy she met from social dating tours. I told her not to trust men she only meets at dating tours. I am a man myself, so I know how men play. However, she got mad when I told her to stop seeing the boy. She’s very hard-headed. What should I do? Should I just let her?