for me it has nothing to do with who is involved, it's the execution, it's the fact that it comes out of the left field, with zero buildup, it's because it damages Mallory as a gf, for springing that onto the MC as a surprise without talking to him first, it's because it paints the MC as the bad guy for denying Mallory and Amanda this, it's because it makes the solo romance seem like settling, instead of the end goal 'If I am enough for you, you are enough for me'
*this part I might be miss remembering, since I played last time on release day* I think you can only refuse them after Amanda kisses Mallory in front of the MC. It's setup in a disrespectful way both to the MC and the player.
I was expecting a throuple ending, just not like this...
And for the first time since I play, analyze and theorycraft about AVNs, it actually kinda bugs me how few people seem to have issue with that. Like I know Mallory is not the most popular, but still, attempted character assassination on the last leg of the race should concern more players.