Women.
2 weeks ago I finally started talking to a girl I was in love for half a year. We discovered that we live in nearby apartment blocks (she moved there a month ago) on the way from the work and started chatting about it. She almost immediately gave me her phone number by herself to send me the list of books she was trying to give away and the same evening I went to her place to pick one of them and chat a bit. The next day we went to our workplace together, I also came up with some excuse to meet her again in the evening and this time we talked for almost an hour. We smiled and laughed a lot and it was surprisingly comfortable. Then she left to her hometown on a vacation for 2 weeks and the last week we chatted 2-3 times per day almost daily. She sent me photos and described her days there and she was very warm to me.
The conclusion to all this was yesterday when during on of our conversation she mentioned that she has a boyfriend. I was so dumbfounded that I couldn't even process this information.
The thing is I was 100% sure that she knew that I like her before this (later when I confronted her I mentioned it and she didn't deny it). So to me it's incomprehensible how someone can think that it's a good idea to toy with other person's feelings like that. I spoke with 2 other girls about it, and one of them said something in lines "us girls, huh:)" and the other one also didn't see anything wrong in situation and said that she just wanted to be friends with me.