I would have to say B. But don't rely on this! Here is my explanation;
High-born would mean that he is more important or in a higher grade. In this text, he refers him to be high-born because he is rich and she loves him. He [not the high-born] Loves her so much, he is there when she is on the boat [or what he refers to], her death, and more places [I have not read this poem in a while].
Then again, don't rely on this answer! I did my best. It was either B. or C. to me. B. made more sense to me, but we are two different people!
