Board Thread:Questions and Answers/@comment-36250700-20190523132021/@comment-27045866-20190523161307

Besides the meta answer that this is all wish fulfillment and people will waifu and marry what they like. The new world guide introduced the Mana Marker which basically advertises that you are looking for a wife of a specific species across a wide area. As far as getting a monster with high requirements he has also said in the new world guide that monsters are all about emotions and desire and will choose average men if they prove that they really want to marry them:

"Yet still, “being a hero” isn't an absolute standard that must be met as a criteria for being chosen as a monster's husband, and the reason why is due to the nature of mamono mana, which causes each other's power to gradually swell by having sex. Even if the male she'd chosen were just an ordinary male, he would eventually develop into an “incubus”, which is a human who transcends human limitations just like a “hero”.

It is precisely the partner that a monster has chosen for herself that will become the most superior of all males and the most delicious treat to her. For monsters, basically, a spouse is a being used to empower each other through sex. Ergo, it is not viewed as an absolute necessity that he be “a superior male in his present condition”. They mostly decide the male who will be their spouse based on other values and criteria. Also, since monsters are beings for whom emotions such as love and fondness are directly tied to sexual desire, ultimately, the man they feel love or fondness towards will seem the most delicious to them.

For that reason, even if a choice is to be made between “an average male” and “the best male”, most monsters would choose the average male who they are “somehow fond of”. If there is an average male with whom a monster has deepened exchanges and “the best male” suddenly shows up, then a monster would probably be certain to choose the average male. This tendency is even true of the highest rank monsters who seek superior males. Since we baphomets also seek a powerful, superior male to become our “big brother”, heroes go right at the top of the list, but even if we perceive that a man is unseasoned and has yet to bloom, he may still have a chance. Also, it's not uncommon for us to fall for men determined to have a baphomet wife who challenge us over and over without giving up, even if they are completely unremarkable."