Unchecked behavioral issues from SO

Its frustrating when you're a childless spouse / significant other to someone with a child. You can't talk about the child in the same context/ways the bioparent would or you're villianized. Even if it's something word-for-word that the parent has said. YOU aren't allowed to say it.

And it's frustrating that you sit back and watch the bioparent and grandparents talk about how much attitude the child has and that the child is portraying the bad / undesirable qualities the child's mother exhibits, but no one tries to stop the child from acting in those ways. They just stand by and comment that the kid is basically being rude, but won't say, 'hey, stop, thats rude'. Or the bioparent says something like 'I don't want to argue with the kid about it tonight' or 'I don't have the energy to argue about it tonight'. It's annoying that everyone complains, but no one tries to fix it or do anything. Everyone thinks if they do, the child will not talk to them, engage with them, they won't work their way to being the child's 'favorite'. And no one has noticed that the kid won't care in about 10 min if they were corrected, because the kid is not capable of playing independently, so they're going to get over it quick.

It's not fair to me that I am already the one sacrificing my time and life to make sure things go smoothly for my SO, that he can spend as much time with his child after work while I plan dinners, make everything, and clean it all up, but he can't use that time to work on how to improve behavior and let it remain unchecked. If the child does something REALLY bad, my SO will step in, but doesn't usually correct overall rudeness/demanding nature of the child.

I had a lot of grace the last few years as my SO was juggling school, work, and time with his child. I figured once all the extra stress was gone from that, he would be more consistent with what he wants to see from his child developmentally either through behavior or by doing more things a kid their age should be doing. It's been about a month of what is the new 'normal' schedule and it's just disheartening to deal with those things. Maybe things will change when he has the child a week at a time, but I feel like the first half of the week with his kid will be time spent making up for missing the kid for a week and the second half prepping for not seeing them for a week.

He can tell I get upset and annoyed, but he thinks I'm annoyed at his child's behavior. Truly, I'm annoyed with the adults that are the care takers in this scenario. No one wants to step up and be the adult or the bad guy, and I feel like I'll get villianized if I say something.