Spousal Hostility between older parents is a major filial problem adult children can face. This will definitely affect the quality of care if one of the spouse is infirm and needing care. Adult children have more challenges managing disputes between their older parents than managing issues pertaining to their health.
Most cordial couple may develop hostility in later years for reasons that are not so severe or almost non-existing. Mental health also contributes to hostile situation between spouses in later years, if one of the spouses suffer from protracted illness and behaves irrationally the spouse with sane mind may find that extremely difficult to adjust with the challenging behaviour.
Adult children can pitch in with support to ease out such situations. Constant professional counselling, interventions from adult children can ease the situation.