Fiction.
The blond guy is envious of his brother (Dev...? Not sure anymore what his name was) and is not really in love with the woman who is promised to Dev.
Unfortunately she falls in love with the envious brother and pretty much ignores the man she is about to marry. People try to warn her, but she doesn't care.
One day the blond one runs away, I think he had betrayed his brother (or something similar), the brothers even fight on a shore, Dev wins, spares his brother, who then runs or sails away.
So afterwards she and Dev finally have a chance to become a couple and soon after they marry.
What genre is it? ••• Historical romance novel.
Physically describe the book -- Hardcover/paper