Penny knew about the truth spell. And as far as she could remember being told, none of the lasting relationships had ever started with the truth spell. Penthea was of the mind that if you could do it without magic, it was better done without magic. And while this was not the response Wyatt had wanted, it wouldn't have been different with the truth spell, it just would have been forgotten by the girl. And Penny had met Sam, she didn't think the older girl would run off and tell the world their secret.
"Some people aren't really built to handle magic, Wyatt." It was something Pen tried to tell her whole family. Maybe she just wasn't built for it. But no one accepted that answer. Of course as far as they knew Sam didn't have any witches in her family, so it was probably more true than it was when Penny said it about herself.