Well these aren't necessarily focused on NTR/Cheating, they do have those kinks along with the pregnancy mechanic:
Peasant's Quest: pregnancy/impregnation is a core mechanic, you can have multiple children with multiple females, pregnancy sex included. There's five women I can think of that have partners you Netori, although two of them eventually have their partners out of the picture, and one of them you can't impregnate yet (WIP)
Manila Shaw: You play as an FMC and can choose to be in a relationship with someone early on, which means all sex afterwards is cheating. Core pregnancy mechanic but that comes in about 1/3 to halfway through the game (WIP)
A Struggle with Sin: There's two or three women I recall with partners you can Netori, although the pregnancy mechanic is only just being gradually implemented, so far you can only impregnate two people ant they're both single though you yourself can get NTR'd if not careful (can be disabled in game options) (WIP)
Impregnation Island: A few women with partners and impregnation/pregnancy
Queen's Diary of Adulterous Mating: Whole point of the game is your husband the King is barren so you secretly go around getting knocked up to perpetuate the royal line. It's average quality but checks off all the boxes
The Tyrant: This game is abandoned now, but you can cuck your stepdad and knock up your mom (and sisters) multiple times or yourself can get cucked if not careful (NTR can be disabled in either cheats or game menu can't remember), but obviously incest so skip if that's not your thing
Silent Pill: You play a married FMC, can get knocked up multiple times from monster enemies via battle mechanic
Leanna's Slice of Life: Married FMC, can get pregnant multiple times from different suitors
LifePlay: A slice of life sim constantly updated, you can impregnate other people's girlfriends/wives but it's easy to get lost in that game. Has in-game cheats to make thing's slightly easier and has free-roam sex scenes, but also buggy (WIP)
Ririru The Wife who used to be a Magical Girl: Pretty average rpgm, you're a married FMC who can get knocked up multiple times via battle mechanics
That's about it from me, the top of the list are the best ones in my opinion, and with the exception of Tyrant and LifePlay all are Wolf/RPGM