Variations and exceptions can occur when people make changes in their own lives and circumstances.
In the modern west, this process typically follows the pattern of the couple moving through levels of Casual Romantic Interest, Committed Romantic Interest, and Marital Anticipation, culminating in Marriage.
Another thing I should mention is that arranged marriage is missing from this chart.
When I say “arranged marriage” I mean that the individual getting married has accepted the decision of someone else as to whom he or she will marry.
In dating, Courtship, and betrothal, the individual getting married has the final say in whom he or she will marry.
Parents, counselors, and friends typically weigh in on the decision to one degree or another, but, ultimately, the bride and groom have the final say on spouse selection.