deterioration — the act or process of deteriorating.
breakup — The breakup of a marriage, relationship, or association is the act of it finishing or coming to an end because the people involved decide that it is not working successfully.
collapse — If a building or other structure collapses, it falls down very suddenly.
decay — When something such as a dead body, a dead plant, or a tooth decays, it is gradually destroyed by a natural process.
decline — If something declines, it becomes less in quantity, importance, or strength.
