Girls who don't have boyfriends usually act differently than those who do.
This is because social networking sites will allow you to share or post your pictures, life events, favorite activities, interests, and views or ideas with people all over the world.
Many of us really love, enjoy, and sometimes even get addicted to social networking sites.
It's not a sure way, but you can sometimes see if someone is in a relationship.
Some people call this Facebook stalking, and technically it's not the best way to find out about someone, but it can spare you and her some embarrassment.
One of the most important things that can help you find out if a girl has a boyfriend or not is your shared or common friends.