How do the last two endings in the game work?
The last two endings are based on your affection stat during a critical conversation where you have diverging route choices (the 'raging hard-on' vs 'trembling hand' choice). In the trembling hand response, there is a flag for $affection >= 60 that can bring up an additional passage if you fall below this value. Similarly, in the raging hard on choice, there's a flag for $affection <= 40 which leads to another route with additional scenes. There's also a flag for $respect <= 40 in one of these routes.