automatically connect to xbox live when I'm in a world , makes the game close alone.

Once connected to xboxlive , to exit and enter the MCPE is necessary to wait a few seconds until you connect to xbox live again automatically if you enter their world before the automatic connection to Xbox Live Be held , automatic connection will be done while you are playing when this happens , your MCPE closes alone.
Normally automatic connection to Xbox Live delay when the Internet is slow.