I read this through an OI lens, and Nicole is the "main character" of the series for me. The story so far seems to be pushing Keios to be the "male lead". I hope Nicole dumps his ass for good and finds a better life where marriage is neither necessary nor sufficient for her happiness.
Claude seems to be on his way to be the "2nd male lead", but I hope they just have a relationship of mutual respect and no more.
Agreed on all counts.
I hope Claude (Lord or otherwise) is there as an initial foil, and then support character for Nicole's efforts to passing the exam and gaining access to studying abroad in Iliegele. No romance, just mutual respect as you said.
I hope Keios doesn't "get Nicole" in the end, and instead takes all of this as an opportunity to grow as a character and as a person, and find a path that fulfills him on his own. He's an oblivious, bullheaded asshat, but he's not a
bad person, so I hate to see him as an antagonistic character that deserves to "lose and suffer". But I hope to the hells that Nicole rids herself of her engagement to him and moves forward as her own person.
Also yes, Nicole is absolutely the "MC". Keios would be "MMC1", and Claude "MMC2".