I’m junior high school I read a teen romance mystery novel about a high school couple who were torn apart by a boy and a girl. It was also Halloween and they were all trying to set up a haunted murder scene that took place many years ago. In the end both the bad boy and girl got busted for trying to harm the nice girl. I also think that there was something with a dress that used to belong to the murdered woman from many years ago and was worn by the nice girl. On the cover is a guy and girl holding each other. I would guess that this book came out in either the 80’s to early 90’s. Thanks.
Lost Classics of Teen Lit: Name That Book! 