Lovelyme, this is probably not the best place to get advice about this, unless you are prepared to accept that most people here do not believe in friendships between boys and girls. Not knowing your daughter, and not knowing the boy, it’s not so glatt to say it’s a good idea or a bad idea. Also, how young a teen is she? 2
If you are yeshivish, then clearly this is not something that is considered acceptable by people in your chevra. If you are a bit more modern frum, it may be routine for boys and girls to meet and mingle in organizations, group activities, etc.
In my teen years, the latter was very commonly done and no one would have thought negatively about it. But we live in different times now, and what was once very acceptable, no longer is. A lot of that is because our society is so pervaded by shmutz that additional steps are needed to keep our kids grounded.
I do think you should talk first with your daughter about your concerns, see where she is in all this, and speak to your rov for guidance.