Bro, walking in on two adults having sex isn't 'cuck content'. Learn what NTR actually means before throwing buzzwords around. She's just with her own guy.
Will this game be a harem game? From what little I've played and those scenes they show, I can say no. All they do is make you want to avoid the mother by showing her with another man. It's a great way to ruin what are personally my favorite things in games: MILFs. Or will this game have cuck /NTR/NTS content in the future? Why introduce the mother then? Is the MC a cuck voyeur who enjoys watching another man fuck the mother? What a waste of time and a waste of a good character
To clarify for anyone reading: the mother/stepmother is a side character, not a main romantic interest. Seeing a secondary character with her own partner is not NTR, NTS, or cuckolding, because she is not the MC's partner to begin with. The game focuses on the actual main characters, like Mia. There is no cuck content here.