Is this a friendship?

TBH I think that I wouldn't bother with her. As I've become older, I've less time for people who aren't real friends. These days I prefer to meet up with people who have time for me. This said, we are all different, so perhaps seeing this person suits you, Stillness? If it really doesn't, then why bother?

Stillness.., You really must stop feeling resentful. Things happen in life. Do what I do, just look forward to your friends next visit.

Sounds a bit like my best friend that was!. Her DH died and she’s got a new man in her life. She’s having a wonderful time, here there and everywhere, it’s almost non stop. I can’t keep up with it all and I miss her🥲.
You think you know your best friend of 25 years very well but you don’t really.
There was never a hint that she would be interested in finding a new man so it came as a terrible shock when she did. I just got chucked on the sideline or that’s how it feels like.
It’s taken 3 years for it to sink in that she’s not going to be around much anymore so I’m getting on with my life. Hers is much more exciting and I wish her well as she spent years looking after her DH extremely well who had Alzheimer’s.

Aveline

Just go with the flow. Enjoy her flying visits and don't expect too much of her.

Yes I agree, if this is what you want, if not just back off

Personally, if you’re not offended by her, I’d just meet up with her if it’s only a few times a year, but you could always be unavailable now and again and see how it goes?

Mismatch of energy. You like a friendship with a bit more to it. She is one of these people that flits everywhere. We had one at our WI a few weeks ago. She was very bubbly, everywhere, full of energy, didn't stop talking and 'Woosh' she was gone. I left the outing thinking 'thank goodness I am not friends with her'.
Focus on the people who are worth your time and energy. You could always treat her as a very superficial contact letting her do all the contacting and arranging. But, up to you what you want. And, remember, you are worthy of good friends.

She is no longer "great buddy" material. Back off slowly and put your energies into more rewarding relationships.

There is that wise saying about relationships:

"The popular phrase, often attributed to a poem by Brian A. "Drew" Chalker,

suggests that people enter our lives for a reason, a season, or a lifetime

This philosophy emphasizes accepting the impermanence of relationships, encouraging gratitude for the growth or support a person brought, rather than harboring resentment when they leave.

so maybe its was a season or a reason.

Just go with the flow. Enjoy her flying visits and don't expect too much of her.

I would just slowly back away. Don’t be available when the next meeting is due. Find other things to interest you. Maybe learn a new hobby or go out with other friends. I had a “friend” like that and everyone around said that we just weren’t suited to each other. It took me a few years to see it and I am a happier person with her not in my life. Take care.

You’ve outgrown each other, it happens.