I'm not sure specifically as I haven't read it in detail. But generally, it might be about a woman's journey to enhance or improve her husband in every possible way, perhaps in terms of his skills, personality, or social status.
I don't know for sure since I haven't read the novel, but I assume the main characters would be the wife who is on the mission of levelling up her husband and the husband himself.
You might consider giving him some space to explore the manga on his own and then discussing it together. Sharing your enthusiasm and showing how it brings you joy could potentially get him on your side.