The reason why people are annoyed is because the choices don't make logical sense. If you're going to push for certain gatekeeping choices to reach certain paths related to who characters end up with, those choices should be a consistent build up.
Polyamory isn't something you just flick a switch on. It's not some BS 'kink' that you can create a situation where one person goes 'Hey, I love this person a lot, and since I do, I'm going to suggest polyamory to him' like Jaye does. And it's definitely not something that someone just randomly agrees to like Mallory does. It’s not fucking anal or bondage, FFS.
In RL, the way polyamory happens with monogamous people is exactly how the so called 'open relationship' path goes. The people involved literally fall in love with the same person, who is completely honest and open about the fact that they are poly, and then decide that having a part of someone they love intensely is better than having nothing at all.
In this story, you only get a unicorn ending (it’s not a ending of the girls aren’t of equal status) if you commit fully to one girl. There is absolutely no wiggle room at all…it starts back when the MC is checking out the girls topless on the boat deck, because you need that extra “love point” to push you over the edge to get the bet on red (Jaye loves you enough to explore with Mallory) or bet on black (Mallory loves you and Amanda) achievements.
In other words, so called polyamory becomes a reward for being completely monogamous, which is exactly the opposite of what anyone should expect. I’m all good with making it difficult to achieve, but my theory is that they realised that most people had managed to get the real throuple path (both being in an open relationship) and instead of making it so that Jaye and Tara were a thing with enough love/trust points, with Tara being the unicorn (which would make sense narratively), they instead ditched that ending and shifted the Jaye/Mallory ending over to Jaye’s path.