This answer is something of a frame challenge. It looks like you've already clearly voiced your displeasure with the situation, and the situation continues despite your displeasure.
So, I'm going to go out on a limb and be the bad guy here, because... Well, the simplest explanation is usually the right explanation.
It sounds like you and this guy had a long distance pseudo relationship. You talk fairly constantly, plan trips together, and most likely flirt. Now he has a local girlfriend/partner and it sounds like he wants to have his cake and eat it too. He wants to have a relationship with the local, and a more casual relationship with you.
Chances are pretty good that he's playing you and this local against each other, because that way he doesn't have to be accountable for either of you being upset. You're upset with the local, and she's likely upset with you, leaving him free to continue both relationships relatively blame free.
My advice would be to call it what it is and take a giant step backwards. He's playing you both, if you don't like how he plays, take your ball and go home.
If you're ok with the arrangement as is, that's your prerogative, but don't delude yourself about what's going on. Accept that there will be less frequent contact, because he's choosing to spend time with someone else. She probably is a little uncomfortable with the amount of contact, but chances are pretty good that he's telling her rather similar things about you being jealous, as he's been telling you about her. It's not her fault that he's choosing to spend his time the way he is, that's his choice whether she likes it or not.
Basically, if you're going to be upset, be upset with him. He's an adult making choices, if he chooses the relationship with the local, she probably didn't force him.
The interpersonal skill here is recognizing when someone may not be being completely honest, and/or may be avoiding accountability for their own feelings/actions. In cases where you've already made your thoughts and feelings known, and the other party hasn't acquiesced, sometimes all you can do is adjust your own expectations of the situation.