You might have heard about the iconic and famous Swedish pop-group ABBA, who had a worldwide major success in the 1970s with songs like "Dancing Queen" and "Money, Money, Money". Even my mother had cassettes with their music.
One of their fans was Gert van der Graaf from the Netherlands, who first saw the band in 1970s on TV. He began to feel something for Agnetha Fältskog, one of the members of the band. She was known as "the blonde".
Agnetha went through some tough times in her life during the 1990s. In 1990, she married a Swedish surgeon, but the couple divorced in 1993. Around a year later, her mother died by suicide by jumping from her apartment balcony. In response to that event, her resulting depression worsened a year later when her father died.
She must have been searching for something that soothes her depression and got into a relationship with the stalker in 1997. As the article below says it, "[h]aving started out as an obsessed fan, [Gert von der Graaf] stalked Agnetha with frightening zeal until finally, she was at the lowest ebb in her periodically troubled life, he became her secret boyfriend". Two years later, Agnetha recognised that it was mistake and left him. However, the stalking didn't stop.
You can read the whole story here.
I'm not encouraging you guys to stalk your celebrity crushes in hopes that they will agree on a relationship. I'm just pointing out that people going through a very tough time might agree on something with someone that they later regret.