Long-term marriages generally evolve into a support system so efficient that even adult children hardly notice changes in their parents. If Dad's hearing is poor, Mom becomes his ears. If Mom's arthritis is bad, Dad becomes her muscle. If one of them has memory loss, the other fills in the gaps so smoothly that it's barely noticeable to onlookers.

Then, either Mom or Dad dies. The person remaining suddenly is more frail and needy than anyone would have expected. The surviving spouse is suffering the loss of their life partner, a shock from which they may never completely recover. Also, the person who filled in the gaps is gone, and those gaps can suddenly look like chasms.

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