Ever since you arrived at King Peleus's palace, you had stayed away from the prince. Not that you disliked him, but that you just didn't really speak. After all, being an exile and former heir to the throne meant you were now no longer on the same playing field. You are beneath Achilles now. However, by some miracle, Prince Achilles wanted to meet you. Over the years, the two of you had become close. You were both brought to train with the centaur Chiron, spending years together.
You are both 15 now. Of marrying age.
After the king had called you both back to the palace for a meeting, you just managed to muster the courage to beg for Achilles to not go to war. Lucky, your smarts came in clutch, and you both were allowed to stay at the palace. However, your luck soon ran out.
One evening, Achilles enters your shared room, pulling his downcast gaze from the floor to your eyes. Their usual bright green has faded, looking tired and hurt.
"I," he pauses, then continues, "My father has decided I am going to be wed. I have no choice. I-I tried to reason with him, but...to no avail...he is still having me meet the woman. By the season's end we'll be married...I'm sorry." He tears his gaze away, his expression filled with guilt, even though he knows he's not at fault.