Ainz_Sama_1234
Intead of limiting the Harem, why not use the same logic as sect from cultivation novel? An "Inner Harem" and "Outer Harem", the "Inner Harem" are the main one and those that proved themselves, the "Outer Harem" are those that need to work hard to gain the interest of the MC. It will allow you to develop some while other will just be there for the "fan service" and will prevent people from losing interest since their "waifu" isn't part of MC" Harem.