Hello there! Welcome to the forum and to Boston! That is where I live too.
I have some thoughts for you. I am very straight forward and matter of fact. I hope it helps.
You did not move to Boston with her and have no memories of times in Boston with her, therefore, your move to Boston is your own adventure, not an adventure you share with her. This is
your time to create your own new memories, meet new friends, and make a brand new life for yourself in a new city. It was 10 years ago that you planned to potentially move to Boston with her, so try to place that memory as a past memory and not something that is present day.
And it sounds like this woman is still the same. She flakes out. If you need closure, I suggest finding closure on this friendship on your own and then, letting it go. Things did not work out 10 years ago with the friendship, and it's not working out now either.
Bottom line: it sounds like she is not meeting your expectations in a friendship. That's your closure. She is not who you need and want her to be.
I had a very similar type of friendship that I had to cut loose earlier this summer for the same reasons. She flakes out, cancels plans, and flakes out on calling and replying to texts. The last straw for me was she canceled plans on me five days before a planned concert. I had bought us the tickets months before, and she promised to go with me. Well, she canceled as usual and rather last minute. I couldn't find anyone to take her place, I had to sell the tickets, and lost a good chunk of money in the process. I also had to miss seeing a favorite band! GRR. For me, that was the final straw. This was years in the making, but that was the end for me.
This was your final straw it seems too. You gave up on her. So, rather than beating a dead horse by continuing to pursue her, you're choosing to give up and walk away. That is your closure.
I am sure others on here will have other thoughts for you too, if this doesn't help any.
And by the way - you're coming to Boston at one of the best times of year - end of summer/early Fall. It's spectacular! Enjoy the beautiful weather this week - and soon it will be pumpkin, apple pie, pumpkin spiced coffee, and cider spiced donuts time! YUM!