Kingdom of white lies

The Rosthorn twins never knew their mother. Their father, brother of the King of South Ascana, barely mentions her. The only thing he did tell them was that Zahra, their mother, disappeared with their older sister 5 days after they were born. Never to be seen again.
Andrea and Alastar have lived in the castle their whole life, together with the King and Queen, their Uncle, their father, his new wife Tasha and their daughter Amelia. Nothing very exciting really happened until on their 18th birthday they found a box with a letter waiting for them in their room.
The letter appears to be from their mother in which she explained how she had to run away almost 18 years ago and that she has been living in the North of Ascana ever since. At the end of the letter, she asked them to come look for her.
Andrea and Alastar decide to follow the instructions in the letter and they leave in the middle of the next night.
On their path they meet a certain boy, Reeve, who accompanies them and takes a certain interest in Andrea.
A story in which bonds will be tested and promises will be broken. Choices must be made. But nothing is always as it seems.
What would you rather believe? The sweet lie or the harsh truth?