par'Mach was the Klingon word for love, but "with more aggressive overtones", as Jadzia Dax once explained to Benjamin Sisko.
In 2373, Worf developed par'Mach for Grilka, but was unable to pursue her because at the time he was regarded as a traitor to the Klingon Empire. Instead, he helped Quark conquer Grilka's affections, and eventually realized that Dax was a much more suitable (and attainable) mate. (DS9: "Looking for par'Mach in All the Wrong Places")