Hey Altanoguzaltan,
After some research, it looks like that the WhatsApp application uses a different protocol for its network requests:
... WhatsApp uses the FunXMPP protocol for message exchange which is a binary-efficient encoded Extensible Messaging and Presence Protocol (XMPP)
So the above means that you couldn't use Fiddler to capture WhatsApp requests because Fiddler Everywhere is a web proxy that only captures HTTP and HTTPS traffic.
Altanoguzaltan