The fact that she told you it's an emotional thing with him is a red flag. While you can't control her or the other guy (and you know what the guy's intentions are) you don't have to get pulled into the drama.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.