I agree with the ML. That is so irresponsible of a parent. It must have been traumatic thinking your father died as a child.
The mother didn't tell or corrected Saki and the father didn't even communicate with Saki within those years.
also, no way the succubus mother survive all those years without a partner :V
It's probably just to tie up the loose end they never addressed of Saki most likely ending up killing MC. So they retconned it and went "actually Succubus aren't bad, k thanks bye."
Man, from begining to end, this manga made no sense, that's fine though, it's enjoyable, and there's always "Majime Succubus Hiiragi-san" if I want peak.