Singling Out the Couples by Stella Duffy

A princess, perfect in every way except one, arrives in London from a land of milk and honey, and sets up home in a Notting Hill tower block. Her self-appointed mission - to break up couples in love. For what she lacks is a heart. With gleeful dedication, she sets about seducing a husband-to-be, prizing apart two devoted gay men, and ensnaring a contentedly married woman. But things start to go wrong: despite herself she becomes fond of one of her lovers, and discovers a tiny heart growing in her chest. The Queen and King, meanwhile, have despatched her brother to stop her. Will he be a match for her? Her magic is stronger, but then he does have a heart of his own ...