In some indigenous societies, I think it was somewhere in Asia but my memory from Anthropology studies is incomplete - where there is a deficit of men, it can be accepted that two women live as a family and one takes on the male role.
This is not a modern phenomenon but a historical one.
The concept behind this was the functioning of society - it was important for survival that there are family groups and no-one left behind. Thus by one person taking on the male role, this was possible.
It is a similar idea to the one @lightonmetal presented, but in a different geographical area.
The philosophical ideas behind the concept have nothing to do with trans, either, rather they were an adaptation to circumstances combined with preservation of their culture - a temporary flex, if you can say so.
I haven't seen any background regarding whether these couples might have been lesbians or otherwise just made the best out of their situation, but perhaps there is research literature about this.
Essentially these concepts are not progressive but conservative. They temporarily permit women to "live as men" or "boys to live as girls" in order to keep their world and society intact, because the adaptation to "too many girls" or "too many men" within the society is much more difficult.
(Similarly to the ladyboys concept, which provides an "option" (if not an easy one) in a conservative society).
I have never read that anyone believed the people involved really change sex. It's a cultural ritual due to specific reasons.