Fiancé's new pot buddy messages

Below are text messages my fiancé received from a girl he smokes up with. They are talking about me. I messaged her "leave (fiancé's name) alone", to which responded with a Ramsey Snow quote. I've never met her. I told him to stop talking and hanging out with her if he wants to stay in a relationship with me. He didn't want to stop talking to her. He said he would only do it to make me happy. Since he's stopped he is acting like his heart is broken.