My Fair Spinster by Rebecca Connolly

The Spinster next door…
Grace Morledge is a failure. Or so her father believes, as she is unmarried despite her many advantages. In his mind, Grace must have significant flaws to be a spinster, and something must be done about them. To her mortification, he demands she be fully examined and all her flaws recorded. And the man he chooses is the worst possible candidate of all.
Aubrey Flint, Lord Ingram, has known Grace since childhood, but he never anticipated Lord Trenwick demand he examine her for flaws. How can perfection have faults? Reluctantly, he accepts the assignment and finds far more than he bargained for, as perfection becomes more and more tempting.