
In an honest answer and not fighting with other people, I would say talk to her. Seriously. And if you suspect cheating, dump her. There is no reason to date someone you do not trust. And if you have no evidence, watch your levels of suspicion ans therefore happiness. When you are no longer happy, leave. If you have proof, leave. If you feel like she lies, leave. She could be making friends and enjoying her stay, but if you do not trust her, do not date her.