To Love, Honour And Betray (Till Divorce Us Do Part) by Kathy Lette

Lucy's been married for so long, her wedding certificate should be in hieroglyphics. When Jasper walks out after eighteen years, she panics. What will she do about vehicle maintenance, shifting heavy objects and Allen keys? Not to mention her rebellious teenage daughter Tally, who blames Lucy for the marital meltdown. Low self-esteem is hereditary: you get it from your kids. While Tally's busy trying to find a loophole in her birth certificate so she can put herself up for adoption, Lucy strives to accept that a child is for life and not just for Christmas. Could teenagers be God's punishment for having sex in the first place?

This is a book about what to do when you fall in love. (Wipe it off your shoes before you walk it all over the carpet.) But above all it's a survival guide for anyone who has realized that the perfect marriage is like an orgasm - many of them are faked.