A very good friend of mine suddenly started avoiding me. Why?

Hi, I am a guy who's working in a software industry. I have recently changed my job for better career opportunity. In my previous organization I had a couple of good friends, both male and female. Even after I left my job we are all still in contact.
I had met this girl at my previous office about some 8 months ago. We both had become very good friends since then. She was a beautiful looking girl. In the beginning I used to like her. But later when I came to know she had a boyfriend I gave up. But we became very good friends. The reason was we always used to leave office together after office hrs. We had some friends accompanying us sometimes but we both used to be there always. Never left without informing each other at least. She is a nice girl and used to be very friendly with all of us, but more with 2 guys of us, and above that with me. I am saying this because she used to share everything about her office problems with a guy from our office none other than me. She had trust in me and I too trusted her always. We had developed a very good emotional bonding between us.
We used to chat after office hours everyday when used to part away after some distance. We both had become addicted to it especially me.
In my last days at office I had become a bit emotional and said her that I will miss her when I will leave the company. She always supported me and used to say we will meet in life later. Now when it was my last day at office, I had bid a farewell to all my friends. I had sensed she had become emotional too when she hugged me before leaving. Later I joined my current organization but we still were in contact and she used to phone me or send me a message sometimes. We were in contact for about 2 months. But suddenly around 15 days back or so, she stopped talking to me. I thought she might be having work stress or something, so I too gave her time and didn't call her or message her. But later on she blocked me from her IM, then she avoided my calls. And later when I had visited my previous office for some official purpose, she even didn't come to meet me. I told her I felt very sad about not meeting her, but she didn't reply. I asked my other friends what happened but they too didn't get a response from her. A friend from our group which used to accompany us told me that she was a little upset since a last few days and used to stay alone. But I didn't get why she stopped talking to me. I tried to find out reasons but got none. I tried to ask her but waste. What left me thinking was that maybe she has got into some trouble in her family or love life because of me. Whatever it is I started feeling guilty for nothing and I doubt she would have shared this with anyone else other than me if I was not the culprit. I don't understand a nature of a girl and maybe a girl will be in a better position to answer this stuff. Please help me.

I'm not a girl, but I can tell you, where there's a will, there's a way. This is where it gets really tricky with messaging and not speaking to someone in person - you don't know for sure if she received your messages. If you are sure she has received them, you've done all you can, just leave her - now is her turn to respond. If she values your "bonding" then she'll not let it go so easily. There is also another possibility, she might think you don't care about her, if you left your previous job where she was and where you saw each other frequently - she might think, if you really cared about the "bonding" with her, you wouldn't have left. As I said, at this point if she received the messages, leave her and give her time to respond - if she cares she will.

On another note, she shouldn't be "bonding" with you if she has a boyfriend. As you can see these bonds are meant to lead to one thing - getting closer and closer to someone - only in rare exceptions can they be platonic. Put yourself in his shoes, and see if you think what she is doing would be ok with you. All that said, if their relationship is strong, it won't matter what you do.

Thanks. But I don't think she has that feeling. Because she was supporting me when I had told her about my decision for leaving the organization. She said, I can seek better opportunities in the company I am currently into. She didn't mind it, as she explained me its a part of life. Everyone has to adjust themselves. Things were going fine till around 2 months. In fact when I was about to visit the office before, I had told her that I would be coming in the evening and we will leave together. She had agreed upon that and was excited about it. But then my plans failed because of some reasons. But then too she wasn't upset or something. All these things started to happen suddenly.

As I said, there is really only one thing for you to do right now, if you are sure she received the messages...and that is to leave it at that and let her respond.