When it comes to reasons for a foreclosure, it's normally one of the Triple D's that is the common cause; Divorce, Death or Debt ...
When many couples separate, neither one alone can cover the mortgage payments. Most often the house is sold and the equity is split to cover past debts. The person who does stay in the house, soon finds themselves falling behind in various payments including the mortgage.
Either an unexpected or long term illness death can bring hardship to a family. Just like a divorce, a single spouse finds themselves trying to make ends meet on one income. Not everyone has enough, if any, insurance coverage for this situation.
The more common issue is a large amount of debt. This can be from spending beyond your means, due to ease of use of credit cards, causing high interest rates and penalties. They could be caught by surprise from lose of job, cut hours, higher fuel costs, medical bills, repairs and overall inflation. Also, they may be experiencing the affect of an ARM increase in mortgage payments.