Thoughts on my past experience with a girl I liked?

Me and this girl matched on Tinder and things started off very well. We talked a lot, got along well and had plenty in common. After a little over a week we met in person and that went well I thought. I told her that I liked her, and she was very flattered by it, and she said that she liked me too. But after a while things started to drop off. She was just talking less and less and would take much longer to reply to me (despite being active on other social media) and every time I tried to arrange to come see her again she’d just say “I’ll let you know” but of course she didn’t. We were supposed to go to the movies together but that never happened, thanks to her cancelling at the last minute on two separate occasions.

Now here is where I think I might’ve just been overreacting or looking too far into it, but when I tagged her in this thing on Facebook about the movie we were supposedly going to see together, she did not acknowledge at all and shortly later tagged another guy in something else, in a thing a *** nonetheless! I felt pretty offended by that.

So then I asked her if she had a thing with that guy instead. She said no and that they were just close friends and had a lot of inside jokes. Everybody I told about that agreed that it was rude and harsh of her and one in particular said it was good by me to call her out on it instead of letting her get away with such sheer rudeness.