There are two theories about the dispute: one theory is that Masakado wanted to marry one of MINAMOTO no Mamoru's daughters, but was denied; the other theory is that Masakado married the daughter of Yoshikane, but she had affairs with MINAMOTO no Mamoru's three sons (MINAMOTO no Tasuku, MINAMOTO no Takashi, and MINAMOTO no Shigeru).
この源護の三人の娘の誰かを将門が妻に望んだが叶わなかったためという説、または、良兼の娘を将門が妻にし、その女を源護の三人の息子（源扶、源隆、源繁）が横恋慕したという説がある。