Birds Are Made For Sunlight BAMFS

You always considered yourself a peaceful person, a copy of your father in serenity, honour and responsibility. When a decision of his shatters your world, you are driven into a secret relationship with Oberyn, Prince of Dorne.
None of you knew something so small would have such great consequences that would change your lives.
A.k.a.: Tired of not living for yourself and to avoid a forced marriage, you run away with Oberyn to Dorne.