A Wallflower's Folly by Amanda Mariel

Lady Olivia Montague's betrothed has ignored her and their contract for years. In the meantime, she has decided to remain unwed, embracing the life of a spinster. The last thing she expects is for her betrothed to come storming back into her life.

Following the death of his parents, William Breckenridge finds himself as the Duke of Thorne and in charge of his three younger sisters. He needs help in the form of a mother and guide for his siblings. Lucky for William, he's already betrothed. All he need do is collect his future duchess. William and Olivia engage in a battle of wills, but the more she resists and he pursues, the more their passions flare. Once the heart is engaged, resistance becomes difficult, but will they give into happily ever after?