What's he waiting for honestly
Apparently he has set some kind of ambiguous ideal self for himself to reach, develop into, before he considers himself to be a good match for Cecilia. To be honest, Cecilia isn't exactly attacking him either. She's perfect happy to keep waiting. It seems like waste of time. If he feels the need to change somehow, he would be in a better position to change once he's married and living in Cecilia, as he would be receiving feedback every day. Otherwise, he's one of the most powerful individuals in that world and quite a jolly fellow, so surely he would be qualified from an objective point of view. It's not like Cecilia's family would be against it either, unsurprisingly.