Kicks Me Out After I Launch

Well, every time I log into Minecraft the launcher works fine then when I hit play it begins to load sometimes it will kick me out right there others it will let me choose a world I want to play but just load for hours and hours, the really annoying part of this is that I just bought this game so I could play with my cousins but I am not allowed to play, please fix this bug because I really want to play with my cousins, please solve my bug