https://en.wikipedia.org/wiki/Kodokushi is the Japanese name for this phenomena. There were several articles about it a few months back, like:

http://www.slate.com/articles/news_and_politics/roads/2015/0...

http://rendezvous.blogs.nytimes.com/2012/03/25/in-japan-lone...

http://qz.com/380685/photos-cleaning-up-after-japans-lonely-...

They say you mentally breakup with your spouse/partner some time before before actually do so. From what little I can glean here, the same can (not always, just can) hold true for dying alone.