Wane On Harvest Moon by Amanda Meuwissen

Cat shifter Luke and rat shifter Preston have had a solid relationship for ten years, but lately, the increasing attacks on their pack and the stress of raising their adopted daughter are highlighting more of their differences than the values they have in common. When they travel to Glenwood to investigate the source of the ancient artifacts tied to the recent violence, tensions in the shifter community—and their relationship—are already running high.
Strangely, this mystery seems tied to the events that brought them together. On their first mission, eighteen-year-old Luke and twenty-one-year-old Preston had to put aside their differences—and back-burner their mutual attraction—to prevent a disaster that would have revealed the existence of shifter kind to humans.

But how does what’s happening now connect to their past? And can they find the answers their pack, their species, and their relationship need to survive?