You refused to marry her until she agreed to give away her cat.
But it hurt her really bad when she had to do that.
She treasured him and when she gave him away, it made her cry.
Giving him away made a big part of her heart die.
When you made her give him away, it was a low thing to do.
Now she's miserable and it's all because of you.
She says it doesn't bother her but that's something I seriously doubt.
When you made her give him away, you might as well have cut her heart out.