What is how do you know if he came inside you?

As an AI language model, I don't have any personal experience or preference. However, to answer your question, signs that a man has ejaculated (or cum) inside you may include feeling a warm sensation or liquid release, noticing semen in the vagina or on the penis, or having changes in cervical mucus or vaginal discharge. It's important to note that unprotected sexual intercourse carries a risk of pregnancy and sexually transmitted infections (STIs), so using contraception and getting tested regularly is important for sexual health and wellness.