This is the default marriage ending. To get this, all you need is a morality rating of 30 or above by the end.
Olive marries a knight, wizard or merchant depending on several factors, mostly related to the Fighter, Magic and Housework Reputations. This grants 20 points to the score. If Olive happens to have a Charisma of 200 or higher, the ending talks about suitors flocking to marry her and describe her as beautiful and fascinating. This gives 40 points to the score.