I have had this happen a couple of times in the past few years and I really hate it, especially when I have been a good friend to them and have done nothing wrong IMO and it literally happens overnight. Both times I have been close friends with them, and they've been very keen to be friends and contacted me a lot, then suddenly dumped me. It has happened in the distant past a couple of times too.
First instance was a couple of years ago. I became friends with a woman and thought we clicked and got on well, and she was very keen and contacted me a lot. We spent a lot of time together. Then suddenly overnight she just stopped talking to me! Literally! She deleted me from FB and walked past me in the street and didn't reply to any texts or calls. I asked her in person if I'd done anything to upset her and she said no, don't be silly, she was busy, etc. But it was obvious the friendship was over, and to this day I still don't think I actually did anything wrong. It was bizarre.
And now I think I have been dumped by another friend. We met on a forum 6 years ago, and have met up a lot of times and been close friends. A while back she stopped replying to texts so I gave up contacting her. She has now stopped replying on my facebook and if I comment on anything of hers my replies are ignored and mutual friends acknowledged, so I guess she has dumped me too.
These women are by no means my only friends, and I do have a wide circle of friends, but obviously it is still a bit hurtful and puzzling to go from being good friends to nothing, with not even a minor explanation.
Do all 'intense' friendships eventually go like this?