Constant ask for plus one

So FH and I have a friend from school who apparently had a gf that he literally never mentioned not once in the many times we met up with him or spoke to him or even a hint of mention anywhere on social media. So we send out invitations and his invitation is addressed only to him and FH gets a text from him soon after asking about his all of a sudden gf. Where she came from idk but apparently they’ve been together for a while. So we discuss it and tell him we will have to see if we have space after we get more RSVP returned. About a week or so later we reach out to him and let him know we do have space and add her to our online rsvp and tell him to complete the rsvp for her. Few days later after we remind him to rsvp for her he tells us that now she won’t be able to make it so he updates her rsvp with a decline. I think that’s the end of it. I was wrong. A few days later, he reaches out to FH again saying his gf can make it now and wants to know if there is still room. Really?? Because we’re sitting around holding this seat open for her that we’re paying 100% for when we also have other guests who have asked if they’re allowed to bring someone if there is space. We were able to make space for a few extras on a first-come first- serve basis. We’re now at our max guest list that we were aiming for budget-wise and he has the nerve to ask YET AGAIN if she’s still not allowed to come. I really can’t fathom that he is this inconsiderate to keep asking about this random girl who no one knew about after he was given the opportunity to bring her and she can’t even go. Why even ask if he didn’t even know 100% that she could even go. We’re definitely not about to pay for her plate for her to not be able to go like 2 days beforehand. Also not to sound gift grabby but this guy isn’t the type to put much effort into actually bringing a gift so I don’t see the point of going out of our way to pay money for this guest who keeps going back and forth on their availability to go and then they don’t even bring a gift.