A Nutcase
This guy told a story about how his friend had gotten himself involved in a relationship with a nutcase. At first, things were going fine. They knew each other beforehand, so transitioning from friends to boyfriend and girlfriend wasn’t too awkward. However, things went south pretty quickly from there.
From then on, she’d stalk the friend and hang out at the window to his classes. She’d even disrupt the professor by leaving crazy notes and making strange noises. The silver lining is that he saw the reality of this cuckoo pretty early in their relationship. The bad news that if he called things off, they’d probably find his remains dumped in the middle of the countryside.