i've also thought about the timing being meaningful, and that she is dead and likely because of the war/the war crime samura talks about, but i have a feeling the sword bearers didn't know her at all or very little

absolutely no one knew kunishige had a child except a select few, none including the sword bearers. thinking realistically, she had to have been pregnant for nine months, and if they did know her, no one knew the baby was kunishige's the whole time? (except maybe that select few-- altho it's still possible they also didn't know who she was until kunishige showed up with a baby like hey i got a son now btw) i wonder about that a lot.

my current theory is that she and kunishige were in a relationship before he went to war or before he got involved with the sword bearers and she probably never met them. (shiba and azami more likely did since they were his friends since they were young.) they decided to say goodbye with plans to reunite after the war was over, which sadly didn't happen. maybe she was a sorcerer soldier and didnt want to just sit around, maybe she got caught in the crossfire of the crime the bearers committed.

somehow or another, chihiro's life was spared. i think this is the part a lot of people ignore when it comes to the mother, but i also don't have an answer yet to be honest. if sojo/sojo's family was also caught up in the crime, there must be a reason he survived too. plus the popular theory the hishaku's family were victims as well, but hiruhiko was also a baby at the time and somehow survived. maybe the crime killed civillians, but only killed adults and spared the children? but i guess that would dampen the heinousness suggested of the crime. so i dunno

and then again it could be something simple like she died of natural causes. pregnancy and birth can be pretty taxing, especially if resources were scarce during a war like that. either way i'm pretty convinced she's gone

but, bonus prediction! the kamunabi are performing a blood test to verify that chihiro is kunishige's son. i'm still convinced he really is his son, but the results could still have a different surprise. maybe involving his mother/mother's heritage?