You're at a family funeral, when this girl walks up to your brother and starts talking to him. They really hit it off, and end up talking the whole night. Unfortunately, at the end of the night, they leave without getting the other's phone number. Not only that, but your brother doesn't even know her name, so there's no way to contact her. The next day, your brother comes and kills you.
What's the most logical explanation of why he would kill you?