Mr. Darcy, the Heir of Pemberley: A Novel (Stand-alone Pride and Prejudice Variations Romantic Escapes)

After the death of her father, Jane becomes the new Mrs. Collins to save the family. Elizabeth Bennet then goes to London in search of her dream of marriage for love.
There, she meets her first crush, Mr. Jonathan Hughes, cousin of a friend of hers and one of Mr. Fitzwilliam Darcy's best friends, the reserved and proud heir of Pemberley.
Mr. Darcy falls in love with Elizabeth and is initially unrequited. He begins courting her in an attempt to make her fall in love with him.
They would have to face a huge obstacle: Lady Anne, who had well-defined ideas of what she considered ideal for the future of her son and her family and would spare no effort to prevent them from being together.
Of the many versions I've read, this was the worst Lady Anne, with even criminal actions and as happens in the real world, she wasn't properly punished. What the story has that really stuck with me is the intensity and beauty of some of the couple's interactions, even at their saddest moment.
Hard not to fall in love.