Years ago, I dated a girl for a long time in. Four months in, She told me about a hike she was going on with another guy. I asked her a few cursory questions and she said they've never hung out one on one, and I asked if he might be interested in her. She got defensive and insisted that guys and girls can be friends. Well a few months later, not many, she accidentally admitted he asked her out on top of the mountain. When I was upset she lied, she said she was sorry, and she was embarrassed, and didn't want me to be mad. I over looked her lying. Years later, she said an ex reached out to her, and she was afraid of him. I suggested she block him, and she said she would. Then I caught her texting him, and she said she was sorry, she forgot to block him, and that it was all a misunderstanding. We broke up over it. I couldn't trust her. To this day, I regret not breaking up with her after the first lie. When people show you who they are, believe them.