Charmed to Death by Yasmine Galenorn

November brings with it the annual windstorms, but another kind of storm is brewing. All over town, people are becoming unhappy with their partners. At Shadow Magic, we’re getting more requests than we can handle for love potions, Be-True charms, Reveal-Cheater spells, and anything you can think of to do with romance and its vagaries.
Granny and I know that something sinister is afoot, but we aren’t sure what. Until Dagda Bruins—the chief of police—asks us for help.
We discover a full-scale magical virus going on that’s causing broken hearts, fights between jilted lovers, and scandalous affairs everywhere. As we try to figure out what’s going on, one fight leads to murder, and the race is on to discover not only the source of this mayhem, but a cure for what’s ailing the lovelorn of Terameth Lake. And if we don’t move soon, the body count’s going to rise as tempers and infidelities escalate.