Parenting 'Tweens (9-12) Support Group
This community is focused on the joys, challenges and concerns faced by parents of tweens (9 to 11 year olds). The major areas of child development include: physical development, perception and sensory development, communication and language development, cognitive development, emotional development and social development.
If you have an open relationship with your daughter you shouldn't have to worry about finding out if she is a virgin, she should be able to tell you.
I don't believe in introducing our children to many things that other children have to go through; however, once they are introduced I feel that they trust they will get an honest answer from me. At least you can comfort your daughter that you do not believe in putting her through this type of stress.
If you are worried about the other girl's emotions, then the school principal is likely a good resource for this age group.
On a different note:
Would you feel totally uncomfortable talking to the friends mom? Maybe there is something going on (an uncle or babysitter or possibly even dad) and maybe the girl was reaching out. It is possible both mom and the daughter can use some support.
It could be tricky to approach this, but if you go to the mom and tell her about the conversation you had with your daughter and just let her know you were both confused and concerned but you do not want to invade their privacy she might just open up. She might shut down, but this is where you can just let her know that your daughter's friends are important to you and you are always there if she needs to talk or vent or anything. Mom's need other mom's to talk to, and your girls will go through a lot together- you might as well start talking now!