I can see there seems to be some people still confused as to how a medieval, male dominated society works. If you wish to play Nephilim with your 2024 morals of a modern day earth, you're free to do so, but expecting it to apply in the lore and story taking place here is downright silly.
There is no such thing as male cheating in Nephilim. A man single or married can take multiple wifes, mistresses, lovers, concubines or whatever else suits him and some women accept it as its the way its always been for them, some of the women may not like it but will still accept it as that's how their society works.
If you're on multiple girls path, the girls will not be yapping on and on about them all being in love with the player in front of each other as they feel that will just cause tension and jealousy. Sometimes a couple of the girls will address their feelings with each other but it will be far from the norm as they mostly prefer to just not think about it.
You can call it cheating, man-whoring, harem, call it pluto if that makes you happy, but that's the how the setting for Nephilim's human society works. If you wish to stay loyal to one girl, do so. If you wish to enjoy the company of all the heroines, do so.
/rant over