I had to edit down the original question into one question. I think that the line “I think we two have found the higher love" is significant for a couple of reasons. It is at the point where Reina and Sergius have been reunited and she says this to him as a statement of what is to be expected from both of them. Yet, the phrase rings hollow as it is evident that neither of them really believe it towards each other. He chases after the maid right after she says it and her intentions towards him are not entirely transparent. The idea of a "higher love" in this life is brought out as something that people aspire to their beloved without really knowing the full implications of why they say what they say. It is a significant line because it shows how the feelings of love can be verbally constructed in certainty, but emotionally represent anything but absolutism. Raina's words are significant because they help to establish the idea of an earthly conception of love and a "higher one." This creates the division between reality and what can exist beyond it that permeates Raina and her changes throughout the drama.