There are various theories concerning the reason behind their decision to divorce: Masanari having an affair with another woman and Fuku being furious over this fact and leaving him; Masanari divorcing Fuku after finding out she had applied for the position without Masanari's permission; Masanori divorcing her since he thought he would lose face if it was said that 'he had been promoted due to his wife's success' having discovered that Fuku had got the position of wet nurse; and Masanari and Fuku pre-arranged their divorce by using the above-mentioned stories as possible grounds in order to enable Masanari to serve Ieyasu.
その経緯については諸説あるが、正成が愛人を作ったと知った福が激怒して家を去ったとする説、勝手に乳母に応募したことに激怒した正成が離縁した説、乳母に採用されたことを知って「女房の御蔭で出世した」と言われるのを恥じて離縁状を出した説、更にこれらの出来事は全て口実で正成を家康に仕官させるために正成と福が示し合わせて離縁したとする説などがある。