Books like When Marrying a Duke....
Helen Dickson
When Marrying a Duke.... is 328 pages, about 6 hours 1 minute at 250 words a minute.
12 books to read next
How long each takes
To Sir Phillip, With Love 7.0 h 
It's in His Kiss 6.8 h 
Whitney, My Love 10.0 h 
The Bridgertons 6.9 h 
On the Way to the Wedding 7.4 h 
The Velvet Promise 6.9 h 
Of Love and Other Demons 3.4 h 
Until You 7.9 h 
The French Lieutenant's Woman 8.2 h 
The Lion's Lady 6.6 h 
Morning Glory 8.0 h 
Voyager 19.1 h Bar height shows length. Estimated at 250 words a minute.