The explanation:
The passage stated that the king was semi-barbaric. Thus, he probably raised her daughter such that she was also barbaric, explaining why she could even bring herself to do such a thing to her lover. As she was the only daughter, the king doted on her and pampered her allowing her to get everything she wanted and she would not let others have what she cannot get. In this case, she would not let the woman, that was chosen for the event, marry her lover. The princess was selfish and also semi-barbaric. I took the above into consideration to arrive at my conclusion for the story.
