Well, some people was like: wtf really? obito became evil because rin died?
http://www.narutobase.net/manga/Naruto/600/12
This week's chapter explains everything:
http://www.narutobase.net/manga/Naruto/603/7
http://www.narutobase.net/manga/Naruto/603/8
He also wants to be in a genjutsu, where...