Romance book prob over 200 pages.Greek or italian themed. I don't think it was a mills and boons but from the same sort of branded books.
To be honest most romance books have similar themes so don't hold out much hope.
Female is named Cassie,something beginning with C I think.
She is forced to marry a man, billionaire? who she has some acquaintance with?
Anyway, she becomes pregnant with his child.
There is a scene in the book where she is out in a boat pos helpin with physio water therapy for an animal. She becomes upset, and dives off the boat swimming a long way under the water and causing alarm to others.
She is a caring person always taking in strays? helping others.
Very sweet, funny, sad book