Unchained Melanie by Judy Astley
Melanie finds herself single again after years of being one half of a couple. Her friends predict loneliness, frustration, disaster. Her parents are convinced she's a failure in life. But Melanie is overwhelmingly excited to be able to do her own thing - she plans a programme of behaving badly, after a lifetime of behaving properly. With her daughter off to university and ex-husband Roger married off at last - to his lamentably young girlfriend whom he accidentally got pregnant at the office party - she has what a teenager would call a Free House, and she intends to make the most of it. But is the single life quite all it's cracked up to be? If no-one needs her any more, what is she really for?
Good secondhand condition, paperback.