>

Except her partner invited them, so they are not tagging along ~they are invited guests who should be treated with the same respect.
They asked for an invitation and it was given. They were told to come. If you did not want them there you should not have invited them. >

To be clear, they asked my partner. I was not involved in the asking process. This was supposed to be small, low key, because I still have a lot of work responsibilities. If they were just going to be at the party, cool, no problem. But they're at my house. Multiple days. They're staying here. That's a little more than a one-off. >

Sounds like you are mad at your partner for doing this without discussing it with you first. But those visitors did absolutely nothing wrong. >

I agree with your header, but then when I start to read your post you just sound like an asshole.
So let me get this straight, you agreed to invite this person to your party and then got mad when you actually had to be a host to them?
It sounds like the correct thing to do in the situation is to not invite this person in the first place, like what the fuck lol.
This person did not invite themselves anywhere, you quite literally admit to inviting them like??? >

OP did not invite them. OP S/O invited them. It seems like OP  S/O was talking "Oh I'm hosting a holiday party" and O/P friend was "that's great, I haven't seen you in a while, do you mind if I come".  OP is not a butthole, she just seems very stressed. If her partner refuses to help her with the grocery shopping or take some of the load off her then  that's a convo about their relationship. >

This is not the guests fault. They asked for and received an invitation. This is 100% on your partner. You should have said unless you are doing this, and this, you need to uninvite them. I cannot handle this extra responsibility. I will not. Do not treat these guests differently or poorly because your partner hoisted extra duties on you. That makes you a jerk. You want to take it out on your partner that's valid, but not on guests who were invited. That's not okay, and makes you a terrible hostess and jerk. You are arguing with people that you should continue treating the guests badly, you shouldn't apologize? It's too late, and if you don't make it clear to the right person ~this will happen again in the future, and it will be as much your fault as your partners~, if not moreso on you. Stop blaming people who were extended invitations. They deserve as much respect as everyone else. Jeez. >

Hence why it's in the unpopular opinion section. I'm being held responsible for someone else's agreement because we live in the same house. 
I have been polite to the guests. Doesn't mean that I think I should be bound by someone else deciding that having guests is a good idea. By your argument, once one person invites someone over, the other person living there is also responsible to host them regardless of inconvenience. You're arguing that people can't have boundaries. Because my partner said yes, I now have to rearrange my life regardless of what I had going on or I'm a jerk. >

Yes, it's your guest too. Don't be an asshole. Your partner is allowed to invite people to your gatherings too. >

Wow you’re a jerk.
This is someone your partner is close to.
If it had been one of your close friends, who asked if they could come, I’m sure you’d have no problem calling them “our” guest and making sure they’re comfortable.
Did it ever occur to you that your partner wants them there?  And that maybe you shouldn’t be a cold-hearted shrew towards your partner’s friends? >

We see my partner's friends almost exclusively, which was why this was so important to be able to see my friends. I literally see their ex-spouse every holiday. I'm not going to apologize for wanting a small gathering with my friends. >


I’m not going to apologize

You should.  Instead of being an adult and communicating that you want to see your friends more often, or just inviting your friends over more, you are opting to be passive-aggressive and give your partner and their friend the cold shoulder.
Parties don’t have to be exclusively your friends or your partner’s friends.  Stop being petty and learn to communicate, instead of taking this juvenile “I’m not going to apologize” stance. >

Agree. It’s never polite to tag along to a social gathering you weren’t initially invited to. It’s rude to the host, since your creating more work for them.