@Someone2Love : There have been others, but ya it seems like the cheater fiancé gets off with no consequences way to often. Though the number of these stories where the grown ups are no where near the scene is also a problem, political arranged marriages need permission of the people who made the arrangements if you want to break them and not suffer backlash, or assassination attempts.
In
The Villainess Is Adored by the Crown Prince of the Neighboring Kingdom
the Fiance loses his position as Crown Prince
Then there is
Of Course, I'll Claim Palimony! where the MC and her father leave the fiancé effectively destitute as the engagement agreement included penalties of it was broken due to infidelity.
One short story I liked was
There is No Reason for Me to Bully You (only has 5 chapters) where the international politics destroy the Princes life.
One I liked, though the manga is rushed, is
The Villainess' Slow Prison Life Began with Her Broken Engagement where the king ends up striping the CP Fiancé of his title. After the MC made his life hell.
Sometimes there are political consequences, one I found amusing was a short story I read a couple years ago, written by
FUNA where the CP was engaged to the MC, and made CP over his older brother, because they wanted to breed an ability she had inherited into the Royal line. Him breaking the engagement (including framing for bullying his pregnant GF) meant he pretty much got a major demotion.