The Deceptive Earl by Isabella Thorne

Lady Charity is the last of her friends to marry, and this summer, she finds Bath lonely.
When Lady Charity Abernathy meets Lord Neville Wentwell, she thinks he is a rogue and a scoundrel who has ruined more than one Lady. She wants nothing but to give him the cut.
Lord Neville Wentwell thinks Lady Charity is outrageous; a woman on the prowl for a husband, and he will have none of it. He has been hurt before… He will not play by her rules, or the ton’s.
But when Lady Charity needs his help, Neville understands and rallies and Charity wonders if she had made a mistake that she cannot repair.
Can love flourish amidst the problems of Neville’s PTSD suffering brother and her Alzheimer's ridden father? Add in two future mother's-in-law who would make Napoleon seem like a sweetheart and their happily ever after seems absolutely impossible. But of course, nothing is impossible to a woman like Charity.
Once Charity has seen the man behind Neville’s devil may care exterior, nothing can keep her from having him, not war nor disease, not even her mother or his!

The Gentlemen of Regency Romance Series are characters in the same universe, but the books themselves can be read as stand alones: front to back or in any which order.