All is Mary and Bright by Kasey Stockton

He’s found the woman he wants to marry—it’s a shame she is already engaged to someone else.
Mary Hatcher traveled to London to procure a trousseau for her upcoming marriage. When she attends the Frost Fair and meets a different man that ignites her interest, she tamps down the unwelcome feelings. But when her host’s son arrives at dinner and she learns he is the man she met at the Frost Fair, she has a new challenge: she must spend the Christmas Season in the same house as him without falling in love.

Andrew Bright, the Earl of Sanders can never live up to his father’s legacy, so why bother trying? When he runs into a charming woman at the Frost Fair and later learns she is his mother’s guest, he is overjoyed. At least, until he learns of her engagement. But friendship with her is better than nothing, until she threatens to push him into doing what he has long avoided—stepping into his father’s shoes.

Five Christmas romances and the Frost Fair that started them all. This is the second book in the clean and sweet Regency romance Belles of Christmas: Frost Fair series. Although this forbidden love romance is a stand-alone novel, the books are best enjoyed when read in order.