Magic Forums

Hello everyone, I am new here. And I would like to know, does a spell have a time frame. How long does a spell last? And does it go back to the sender on its own. The reason for the question, my boyfriend(40's) told me that he dated a girl in his late teens, early 20's and was told by a family member of her. That would make sure he was never going to be happy. He doesn't believe in that stuff. Does it matter if the person believes or doesn't in order to work?
Thanks for any info.