From Pemberley to Gretna Green by Laraba Kendig

Elizabeth Bennet is devastated by her sister’s elopement. Mr. Darcy’s ardent love for her leaves him no choice but to act.

Mr. Darcy has finally accepted that he wishes only for Elizabeth, and when they meet at Pemberley, he speaks plainly of his devotion. Despite their uncertain future, he is determined to assist the Bennet family – surely no young lady, however foolish, deserves to be Mrs. Wickham. And Darcy has a plan.
Jane falls prey to bewilderment and anger as Bingley returns to Hertfordshire. He hopes to renew their courtship, but Jane’s world was shaken by his departure and the cruelty of his sisters, and her views of those around her have changed considerably.
In the months since Elizabeth rejected his proposal, she has realized she cares greatly for Mr. Darcy. As they travel along the Great North Road to Gretna Green, they are able to enjoy one another’s companionship and conversation. But not everyone is pleased by Darcy’s involvement.

Over 500 pages. This is a sweet and clean, low angst Pride and Prejudice variation where all of the Bennet sisters have happy endings.