Huge fight with LDR partner. Is this relationship ending?

He can find the time to meet someone else and will travel to do so. He can't find the time to see you. Factually that's incredibly hurtful. I would consider it over

What does "squeeze in" seeing you, translate to, I wonder?

I'm treating another woman to drinks and dinner, but I'll pop in at some point for a quick shag with you?

Throw this one back.

It's over. He is showing you how important (not) you are. Just end it.

He’s testing you to see if you’re ok with his plans. He fully intends to shop around, do you want to continue with him?
YANBU to tell him no.
It’s very hurtful to make that journey for another woman, but not you. It’s also lack of creativity to take her to the same city he spent time in with you.

I would consider this relationship over.

I think it is completely understandable for you to be feeling really hurt by this and to question your relationship.

I can maaaybe see that if this woman were some important business contact / potential client, he would want to invest time in cultivating that.

I also disagree with your notion that a man in a relationship with you shouldn't be able to make new female friends and vice versa. Personally my husband and I both have friends of both sexes, including some made more recently through work, and neither of us feel threatened by that.

But... and they are big buts.

1. Wining and dining a 'new friend' in a city hours away seems very 'extra' and I would be deeply uncomfortable with a partner of mine doing that.
2. If your partner didn't have the time or inclination to make the journey to your city to see you but has the time to do it with someone they just met, that suggests a serious lack of enthusiasm for / prioritisation of your relationship.

He’s not taking you seriously I’m afraid and if you don’t wish to be one of his booty calls, it is the end. Better for you to control the ending. Good luck and sorry.

Yes, that’s a bit odd.
The bit about being ‘allowed’ to make new friends is a bit of a red herring. I think you tend to make friends organically, for example, through shared interests or because you have mutual friends and that is perfectly normal. But this meeting is not organic, your partner has told you he won’t be able to see you and then has made detailed arrangements to meet this other woman and had not planned to tell you. And even if he was networking, surely one part of the itinerary would be sufficient.

People in relationships are perfectly allowed to have and make friends of the opposite sex. Doing what he is doing is not that and it sounds sketchy as hell that he’s effectively taking this woman on a date, hid it until now and wasn’t even planning on seeing you. Weird and huge red flag.

Well, it would be over for me, I can assure you of that. He's dating another woman, and I don't care what bullshit excuses he's using to try and smooth this over. I am sure this isn't the only time he's done this.

No, he obviously wants to start playing hide the pickle with these other women.