This game has belly bulge/stomach deformation? Due to MC's cock size
Maybe could add some futuristic tech that helps the MC make their cock larger?
Also I was about to request some monster girls but then you said this is supposed to be more realistic so... I guess I won't do that hahaha
Only thing I can think of is the kink "impregnation request". Unsure if it's in the game or not. Basically it's just the girl begging to get knocked up.