@Russia0916, you should stick with your girlfriend, she is really nice , independent and mature. It will be hard for you to meet another Russian girl like her. Ask her friend to move back to her parent's place. Having her friend living together with both of you will cause issues here and there. If your girlfriend's friend has her own boyfriend, and all of you live together, it might be ok. Since she is single, you need to tell her that she should go back to her own family, but it's ok for her to visit you guys anytime she wants.