There doesn't need to be anyone pulling strings for there to be back-stabbing, people at each other's throats, alliances, feuds, you name it. Politicians of any party are normal people, not holy martyrs. The colour of their politics doesn't make them perfect, and if you think it does then what you are looking for is a messiah.
NOTE By saying that I did not attack Corbyn! I have nothing against the man. It was about human nature vs conspiracy theories.
Though I daresay that while the honeymoon goes on anything other than uncritical adoration will be construed as an attack.