Besides a select few characters, all playable characters can fall in love with a playable character of the opposite gender. Which couples form are directly affected by what the player does. This is important in the First Generation because if a female is married, their children will appear as playable characters in the Second Generation (otherwise you will instead get their often inferior Substitute characters).
Female characters start off with a certain amount of Love points with all the male characters. Each turn (but only up to Turn 50), they will gain Love points (the exact number depends on the male) with each male. Love growth can be sped up by making females wait adjacent to males (making the couple gain 5 extra Love growth per turn) or by initiating specific, time-limited events. Love growth is further affected by a hidden Jealousy System.
Once a female reaches 500 love points with a male, they become married. Whilst married, the couple have the option to give each other all their Gold and they also receive the Combination bonus if they fight adjacent to one another.