Rivals are a sore subject with many fans of the series. Some gamers don’t want their love interest to get swept away from them while they’re busy tending to their farm. While I can understand some jealousy, the newest games have totally removed the feature. Your farmer is the only one that can get married. The rest of the candidates end up alone, forever, or until you put down the game. This just seems really sad.
In Harvest Moon: Friends of Mineral Town (or Harvest Moon: Back to Nature), after getting married, you could help others discover love. I found it fun to help the other candidates get their happily ever after. But if I was not yet married and trying to romance a candidate, I found it a motivator to work harder to impress them.
Aside from rivals, it would be fun to help other non-romanceable villagers get married. In Story of Seasons: Trio of Towns, helping Miranda romance Frank would have been a welcomed addition.