Yet another good friend of Manfred would be Leutnant Alfred Gerstenberg. Quoting from
The Red Baron Combat Wing by Peter Kilduff: "He and Richthofen had begun their military careers in the same regiment and then served together in Kaghol 2 in Russia. Gerstenberg was a willing pupil and tried very hard to shoot down enemy aircraft. He was unsuccessful, but was one of the few non-scoring fighter pilots retained in Jasta 11."
The fact that Gerstenberg was allowed to remain in Jasta 11 certainly speaks a great deal about the strength of their friendship since those who didn't perform were transferred out.
Gerstenberg was also the one who cared for Manfred's Great Dane, Moritz, after Manfred's death.
The pattern here shows that the Rittmeister's best friends were those whom he met early in his career. As the war progressed, it was very emotionally hazardous to develop any close relationships since one could be here today and gone tomorrow.
Regards...FliegerJG1