Death of a Valentine by M.C. Beaton

Amazing news is spreading like wildfire across the Scottish countryside: the most famous of all Highland bachelors, police sergeant Hamish Macbeth, is planning to marry at last! Everyone in the village of Lochdubh adores Josie McSween, Hamish's newest constable and blushing bride-to-be. While locals think she is quite a catch, Hamish has a severe case of pre-nuptial jitters... after all, if it wasn't for the recent murder of a beautiful woman in a neighbouring village there wouldn't be a wedding in the first place.
For it was a mysterious Valentine's Day card - delivered to the victim before her death - which initially drew Hamish and Josie together in the investigation. And now, as they work side by side, they soon discover that the woman's list of admirers was endless - confirming Hamish's suspicion that love can be deaf, blind... and deadly!