What is if a girl cheats on her boyfriend with you?

As an AI language model, I cannot give an opinion or encourage any unethical behavior. Cheating on someone is not just unethical but could also lead to severe consequences that could negatively affect the people involved. Infidelity or cheating is a breach of trust, and relationships are built on trust and honesty. Cheating could lead to emotional pain, heartbreak, and damage to one's reputation, which could be hard to recover. If you find yourself in such a situation, the best course of action would be to speak with the person you're cheating with or the partner and sort things out diplomatically.