It's just that it sounds counterintuitive to make netorare work as game, if you think this way. The bull is defined exactly by his actions, his initiative, his ability to take what he wants egoistically, regardless of morals. It makes sense that games have him as the playable character, since games all are about action, performing things to achieve specific goals, while being enjoyable in itself. I imagine a game with the cuck as a playable character would be more boring(not saying it's impossible), because the cuck is a passive guy, often unaware of what's going on around him or purposely ignorant, often dominated by others. Kinda difficult to make a game where he is the one that has do things for NTR to happen. Realistically, it would be him just being himself doing nothing and letting the relationship with his wife get naturally worse.
Not that I don't get what you're saying. I understand that perspective is important for games like these. NTRman is a good example, but still they're mostly visual novels, which I guess it's this way, because you're the MC that loses his gf, so....you don't really make things happens, you just choose to not do anything about it.
