"Sorceror's Ward" by Barbara Hambly
Barbara Hambly is one of my favourite authors and I just buy anything she's written without thinking about it, so it's not surprising I like this book :) The heroine, Kyra Peldrin, is a wizard. She's fairly low-level and the story opens with all her magic going wrong for unexplained reasons. Then we find her arriving at her parents' home in time for her sister's wedding. It very quickly becomes clear that despite their powers wizards don't rule this world, and are fenced about with restrictions. Common people dislike and distrust them, having one in the family is a social embarassment. It is also obvious that Kyra, like many of Hambly's heroines, doesn't fit into her world's conception of an ideal woman. She is over-educated, unfashionable and prone to speaking her mind. This is a story with a happy ending, but there are some very unexpected plot twists so the happy ending probably isn't the one you'd predict!
One of the reasons I like this book, and Hambly's other books, is that although there are wizards, they can't do just anything. Her heroes and heroines are generally more likeable because it is quite clear that they are human and haven't got everything. It is a really good story, and sucks you in so much that you don't want to put it down.