I suspect "middle ground" means: stopping a process right there where you want it to stop. And I just think this is not probable in real life and especially in porn logic. He has to be able to say "no" once. Otherwise such dynamics go further and further. This is not a negotiation where you can meet in the "middle". So maybe it's clearer now where I see a contradiction here: a story is a process. If you put a lamborghini and a vw golf at the starting point of the race you can't expect them to find middle ground at the end of the race and reach a compromise. It will play out to the max according to the characteristics you give them at the start.
In a way this is again the topic of the relation between story and choice. If you want a choice according to your personal preferences you interrupt the logic of the story.
I'll be honest with you, I don't have a clue what you're trying to get at here. When I said "no middle ground" in reference to your initial response, I mean that you seemed to be suggesting that the male character is weak and therefore it's only a matter of time before he's in a chastity cage guzzling cum from his wife's furry cup. If you have that as one extreme, and "strong alpha male" (I hate that term) on the other side, then middle ground is quite literally the space between those two extremes.
The game is full of choices, so both the MMC and the FMC are shaped by the options you pick. There are plenty of points where you can say no, or even where you can go partway down a path without it meaning that you want to go all the way as far as the path leads. That gives you plenty of room for middle ground. Even if you go along with the perceived "weaker" choices though (from the MMC viewpoint), he still isn't anywhere near being a "weak simp", IMO.
