Dysfunctional families produce dysfunctional children, who marry dysfunctional people and produce dysfunctional families.  And so, the circle goes unbroken.

If you are unsure if your present SO is dysfunctional, look at her family.   Are the parents still married?  How about the siblings?  Have any of them done jail time or been committed?  While your SO may seem perfectly normal, if she comes from a dysfunctional family, there will be extra baggage with the relationship so be prepared.