My friend introduced me to a boyfriend, and later I learned that he was love rat, full of lies and flawless. Cheating. She said she didn't know until later?

Your friend introduced you to show that she has some understanding and recognition of this boy, but she introduced you to a bad boy and even confessed to you after breaking up, indicating that your friend didn't really think of you. Maybe in her eyes, your friend is not as important as this boy. Maybe your friend was cheated by the boy's appearance. In short, be careful with friends. Such friends also need to keep a certain distance.