Noelle's argument was watertight. While harems have existed since time immemorial, it was impossible for everyone in the harem to receive love equally. In her example, rather than let everyone die. It would be better to let one receive my full heart and survive.
It was an amazing analogy because it represented a life of happiness. Rather than making everyone miserable, it would technically be better to choose one and let the others find someone else.
"It seems that you are not convinced. Then let me go one step further. Say you marry them all. Suppose one of them is kidnapped. Would you leave six of your wives unprotected to save the one who was kidnapped?"
If such a thing really happened, it would be a hard choice. If I chose the six, I would be proving to Noelle that I didn't love the one who was taken. If I chose the one to be saved, it would mean that even six of the girls had less value in my eyes.