I 'dumped' a friend, and have been dumped too, it isn''t pleasant.
I heard from a mutual friend that the friend I dumped couldn't understand why, always been great friends, it was me being weird etc, but it wasn't true. We had been great friends, but we'd grown apart - I was getting married, wanted children, bought a house etc, whereas she was single, going clubbing a lot, focusing on her career.
Not a problem to me, I was happy to hear about her life, but she just couldn't stop sneering at my choices. She took the mick out of me for buying a house in the suburbs, got annoyed at me for not being willing to cancel a long standing plan with the inlaws to go to a gig, sneered at my clothes telling me I looked mumsy (dark blue bootcut jeans, instead of pale skinnies). She thought I was dull for not being willing to blow £££ in topshop or go out getting smashed every weekend. I called her on it a few times, but it was always me being boring or uncool or just a joke 
I eventually dumped her a few weeks before my wedding. I was telling her about plans and mentioned that I'd been shopping for honeymoon clothes. She asked disinterestedly where I was going (booked a year, talked about it loads) then sneered 'Oh. Are you still set on going there then? Why don't you go somewhere interesting?' I just thought, screw it. She has no interest in me, thinks I'm dull and can't even feign an interest in something I'm really excited about. I'd tried to talk about it previously, but she'd dismissed me, so I wasn't making an effort this time. I just stopped answering her calls or messages, and just deleted her from facebook after a few months, when I felt sure I really wasn't bothered about her.
It amazes me that she tells friends she couldn't understand why I dumped her, it upset her so much etc. I'm more surprised that she didn't just dump me when she clearly didn't have much interest in me!