The Kissing Bough by Ellis, Madelynne

Viola Marsh has been forced to live an austere life, locked away under the watchful eye of her spinster aunt. Only on Christmas Eve is she allowed her freedom, to take part in the tradition of wassailing.

Cousins, Percy Gilling and Lord William Ricborough share a close and special relationship, and they require a very particular woman to satisfy their needs. What they’re not expecting is to find her poised beneath the mistletoe on a wintery hilltop.