It depends on how you interpret it. While reading it, I interpret it as he means to say that love is as innocent as a person can make it. When he states she walks in beauty, he is most likely referring to the idea that she is beautiful and has a innocent lifestyle. My apologies if this is not the answer you are looking for.
She is creating a metaphor to convey the idea that love is hard won.
The king had the motive to send a message to all the subjects of his kingdom that if anybody commite a crime he will also be put in the arena and will be eaten up by ferocious animals like tiger
In the story one yound man in love of the princes which is forbidden in that country as the man is not from the family of king
So the young man was put in the arena to face a tiger.
