Oblivious NTR can get depressing too after the NTR reveal near the end lol. But I get what you mean.
The focus of western NTR based on concepts of cuckoldry is usually on the guy. Often, they even decide to make it strictly male MC POV, so he pretty much witnesses the entire thing play out if the players are to see anything. That's usually fine in terms of characterization if it's more of a netorase vibe thing (although I find netorase boring personally), but there are those unwilling cuckolded MCs who is aware of what's happening pretty much instantly. So the narrative focus is on the male MC's humiliation, internal thought process, and just a whole lot of cuckoldry shenanigans by the MC. I think in general, it's designed to appeal more to the people who want to identify with the cuck MC, whether role playing or self inserting.
For Japanese NTR, the focus is much more towards the female getting corrupted, even if the player only controls the male MC. That's where the oblivious male MC comes in. The MC is oblivious, but the player is not, because there are usually multiple POV or recollection room things going on where we can see the process of the corruption. This makes it more fappable for people who enjoy the female corruption, moral degeneration, and cheating, rather than getting aroused mainly from the male MC's cucky nature.