It's not just you. From what I recall (had to delete the game) the AI inputs as late as possible, which allows it to predict your moves if you press a key too early. At the highest difficulty, it can be literally unwinnable due to this unless you are lucky enough to press the same key as it will already be decided when you see what was pressed.
Lust scales with physical damage dealt (you can show up those values with the Tab key; the closer it is to 250, the more lust damage will be inflicted; upon release, some health is recovered, which makes it harder to consistently deal high lust damage). 1-button/mash are explained in the readme and don't change much if at all as far as I noticed; 1-button has the advantage to immediately deal all the lust damage so you don't have to wait forever for an animation you didn't want to see or you want to end it quickly (or you can just let it loop for as long as you want to until you press a button).
If the AI wins in 2 moves, that means you're allowing too many hits. I don't remember ever getting 50 lust damage in one go even at 250 physical damage, but that would be the only way for it to happen since you cum at 100 lust damage. Three makes sense at average damage; at next to no physical damage dealt, you may need more than ten.
The AI is also cheating when stripping you - it does so before the physical damage threshold would normally allow it to. I've only seen it happen on Hard but I don't think it's supposed to happen.
I don't think there's any cheat implemented. As for tactics against the AI, denying hits and grabbing from as far as possible to avoid hitboxes to connect is one way to avoid getting stuck into an unblockable submission hold followed by sex. Breaking your own combos and canceling into a submission/grab also works since the AI usually will attempt to block the full combo and be unable to block that.
It can still counter the move by scanning your input, so if it does so, immediately recover and back away before it is able to try that with you too and force you into an infinite.