It is an insidious assumption to me, personally. I have been living on my own since midway through the pandemic, and have been enjoying it. My productivity has gone through the roof, and I feel grateful to be alive – I've enjoyed the ability to spend time rediscovering who I am when not constrained by constant micro-pressures of social gatherings. The best is the endless ability to cancel social engagements without feeling any repercussions – there's always the excuse of the pandemic.
My mother has also consciously decided to live completely on her own throughout this time, and I've seen her make some tremendous personal growth during this time (more than in the past 20 years, which were filled with a handful of male partners).
Being familiar with Japan's recent problematic (lack of) discourse around the issue of domestic abuse, this statement (especially on the heels of the women telling the source that they have problems with family and boyfriends) seemed facile.
I'm startled by your use of "indisputable fact" there – anything branded as "indisputable fact" is a lofty claim, especially when it comes to lived experience or subjective states of others. We're just willing to no longer investigate the cause of this sudden jump in suicides, because we can simply write it off as "normal" loneliness? I don't like it when others presume to tell me what is "normal" for my (or any) gender, especially when a mysterious jump in mortality is involved.