I traded with user GW2 account for Steam account. We did the trade but we agreed not to change passwords / emails until the guild wars 2 email gets changed (you have to do it so that you email support). I woke up the other day and I noticed that he added 2 step authenticator on my GW2 account and I asked him why is that. He replied that he forgot to tell me. Then in matter of seconds I got logged of HIS steam that I traded for and he deletes me from skype.
So.. conclusion is that he gave me negative rating for scamming ME, which is funny how this system works and there is no way to prevent this shit from happening.
Also, yes, we traded before, and yes, i recovered my steam that we traded in different trade because he is douchebag.