Petunia Elaine Dursley (nee Evans) is a canon character in the Harry Potter books, wife of Vernon Dursley. She is the nonmagical elder sister of Lily Evans. She resents Lily for her magic, calling her a "freak".
Petunia does not seem to get what the magical world means to Lily, and how "real" it is, and at one time she ask Lily when she is going to stop it, and go study something in the real world.
Petunia Marries Vernon in chapter 26. "the Wedding".