It's starts in France with three sisters the oldest Elizabeth (aka bessie, Lisbet) is considered a spinster who was left at the alter, but really the guy had an affair with one of her sisters, which we find out towards the end, while her two younger sisters are married, she get asked to dance by a Frenchman. She has a complex with her body image and is a doormat. They return home to America and run into the guy she danced with who was at the time pretending to be his titled older brother who didn't want to attend the ball. They all think he is trying to keep his real identity a secret but he isn't he is being himself. They marry the older sister to him. He calls her Lisbet instead of Bessie cause that's a cows name. Je t'adore (Shut the door?) is a joke between them. He spanks her with a slipper. His brother's name is Adam. He's trying to start a shipping company and they spend their honeymoon in Bahamas were they fall in love but malaria breaks out and he puts her on a boat home before they close the port. She thinks he doesn't love her but realizes she's pregnant and goes to France to find him. He's made his fortune and they go back to America and she realizes that her sister's perfect marriages aren't true love and gives them pieces of her amythest jewelry.

This has to be Wicked Stranger by Louisa Rawlings. I have this novel.