When someone blatantly lies to you, walk away. That is sign of disrespect and very dangerous. It is a deliberate intention to deceive you.
So, red flag for any type of relationship. Its toxic and potentially harmful for you. Cut ties fast. From anyone who lies, they certainly do not have your best interest at heart.
Usually when someone blatantly lies they will tell you, get confused in a lie. Confronting their behavior usually brings this to light.