Why did Henry VIII think Anne Boleyn was having an affair with another man?

When Anne miscarried a male child, Henry declared that their marriage was the product of witchcraft. Henry explored ways in which he could leave Anne without having to go back to his first wife. Anne was arrested with the charges of adultery, incest with her brother and treason. The charges had little, if any, evidence behind them, but the Queen was still found guilty and executed, along with her brother and numerous men who were accused of being her lovers.