There are many misconceptions among players as to the Rival heart events in Harvest Moon games. First among these is the confusion between Heart Events and Rival Heart Events.
Heart Events are events that occur between your character and a prospective spouse when you have reached a specific minimum affection level with that individual. In other words, the Purple Heart Event or 2nd Heart Event can be experienced when the individual reaches Purple Heart level OR higher. At deepest red heart, you still could experience all heart events from Black to Yellow. The prospective spouse's heart level NEVER CAN BE TOO HIGH to trigger one of the heart events.
You cannot miss heart events and they must be experienced in order. If you give the 'correct' response to a question or proposed action in the course of the heart event, the affection level of the proposed spouse will be boosted. In HM DS and HM Cute DS, AP is boosted by 3000 points when you give the desired response...
Giving the 'wrong' response will not prevent you from marrying the proposed spouse nor will it prevent you from triggering the next Heart Event when the required affection level is met. What it will do is decrease the affection level, setting you back a little in the progress of the courtship. In HM Cute DS, there is one bachelor whose heart events are divided into two parts. This is Skye. You need experience only the first part of each of his heart events in order to be able to experience the next one... again, though, missing the second part of any heart event will reduce his affection level a little. Provided there are no season requirements that prevent one from experiencing any heart event in the first year, ALL four heart events usually can be experienced in the first year, allowing your character to marry before the end of the first year of gameplay, again provided all general requirements for marriage are met as well.
Rival Heart Events are the events that allow your rival's courtship of an eligible bachelor or girl to advance. In order to experience Rival Heart Events, the affection level of the proposed spouse must be at a specific level OR LOWER. In other words, unlike the Heart Events that can be experienced even at a level that is HIGHER than that required, a rival heart event will not trigger if the heart level is too high.
Once you reach deepest red heart level with a proposed spouse, rival heart events no longer will trigger. HOWEVER... to respond to a comment by some one, this is NOT a permanent state of affairs. One can LOWER the heart level of the eligible girl or bachelor in order to trigger the rival heart events if one decides one would prefer the individual to marry the rival... I have done this again and again in Harvest Moon games. I like to experience all possible events in any Harvest Moon game. In many of them, including FoMT/MFoMT and HM DS/HM Cute DS, each event is worth a specific number of points towards your Farming Degree. By experiencing ALL four heart events and all four Rival Heart Events as well, you gain maximum points towards your Farming Degree.
I will explain the method I use to do this, but first give a few more details about the Rival Heart Events. Like Heart Events, there are four rival heart events for each eligible bachelor or girl. These are Black, Blue, Green and Orange. Unlike the Heart Events, all of which can be experienced in the first year, only the first or Black Rival Heart Event can be triggered in the first year. The second Rival Heart Event or Blue Rival Heart event cannot be triggered before the Second Year. The third or Green Rival Heart Event cannot be triggered before the third year of gameplay and the fourth and final Rival Heart Event, otherwise known as the Orange Heart Event cannot be triggered before the fourth year of gameplay.
The reason for this is to load the marriage deck, as it were, in your favour. You have four years to win the bachelor or girl of your choice before there is ANY chance of your rival taking her away from you.
In my own games, I raise ALL eligible girls or bachelors to full red heart level in my first year if possible, experiencing all four of their heart events. One really does not need to raise their hearts to red heart level but only to yellow in order to experience all four of the Heart Events. I raise them to red only in order to be able to experience the Marriage Proposal Event and subsequent wedding for my guides. I do not SAVE the results or I would be married. There is no going back once the proposal is accepted!
At the start of the second year or after the Spring Festival, I then begin the painful process of LOWERING the heart levels of the bachelors or girls I do not intend to marry in order to be able to trigger the Second Rival Heart Event. If the bachelor or girl is at any level that is HIGHER than blue, the second Rival Heart event will not trigger. I therefore have to lower the heart level from Red to Blue.
There is an easy way to do this in HM DS and HM Cute DS. Each eligible girl or bachelor has one item that he/she utterly detests and which will lower AP by a full 5000 AP point and 20 FP points! I call it the 'Secret Weapon of Hate' and this information is included in my Courtship and Marriage Guide. It is unfortunate that it lowers FP as well as AP as FP does not affect heart events. For Marlin, for example, the Secret Weapon of Hate is Butter. Give him a gift of Butter and his AP will drop by 5000 points, half a full level. Give him butter for two days and you can reduce his AP from Red to Orange. Two more days will reduce it to Yellow and two more will bring it down to Green. Two final gifts of Butter will reduce it to the required Blue level in order to be able to trigger the Second Rival Heart Event.
This effectively means that, even if I have the bachelors or girls at red heart at the start of the second Spring, I can reduce their heart level sufficiently to be able to trigger the Second Rival Heart Event for each before the end of Spring in the first year. If you look at my 2nd Year Events Guide for HM DS, you will see that I did this in fact in the original 'boy version' of Harvest Moon for DS. I am doing the same in Cute and compiling my 2nd Year Events Guide now.
At the same time that I reduce heart levels using the 'Secret Weapon of Hate', I restore FP by giving them subsequent gifts each day until I have raised FP 20 points again. Remember that a second or subsequent gift does not affect AP but will affect FP. It can be a rather expensive strategy, but it works. I don't like to have any one at less than maximum FP.
By the second year, I have every one at 255 FP and have experienced all the events that depended on specific levels of FP in the first year... those events all are included usually in the First Year Events Guide. Maximum FP therefore no longer is strictly necessary, but I am very emotional where Harvest Moon is concerned and like to know that my character is universally loved! You can't do this in the real world quite as easily, alas...
All that is required, then, after experienced the Second Rival Heart event in the second year is that you raise the bachelor or girl's heart level to Green before the start of the third year in order to experience the Third Rival Heart event at the earliest possible opportunity. Raise the heart level to Yellow or Orange in the fourth year to experience the Fourth and final Rival Heart Event.
There is something that one needs to know with respect to the 4th Rival Heart Event. If you trigger it, YOUR RIVAL WILL MARRY THE GIRL OR BACHELOR ONE WEEK LATER. There is no way to prevent this from occurring, so if YOU wish to marry the individual yourself, you must not experience the fourth rival heart event. In my own games, I am long married to the individual of my choice before the fourth year, which is the earliest opportunity to trigger the fourth Rival Heart Event. Remember: experiencing the 4th Rival Heart Event guarantees the marriage of the individual to your rival!
In FoMT/MFoMT and HM DS/HM Cute DS, an invitation to the wedding of your rival depends on your friendship level with your rival. If you are at maximum friendship level with your rival, you will receive an invitation to the wedding.
There is a real advantage when you allow other couples to marry. There are a number of events that only occur in the game if other couples have married. Remember that all events are worth points in terms of your Farming Degree. Even if they had no 'point' value, however, I always would make certain that every one else in my village had the happiest possible life. One of the reasons I like the idea of marrying Skye or one of the Mineral Town bachelors in Cute is because it does not deprive any of my 'rivals' of the chance to marry. In the original HM DS, I preferred marriage to one of the Magical Girls for the same reason.
Some players are apt to confuse Rival Heart Events with true Heart Events. Remember that the only Rival Heart event that can be experienced in the first year is the 1st Rival Heart Event or Rival Black Heart Event. I actually include the full text of every Heart Event and every Rival Heart Event in my guides. If a player is not certain which event he/she has experienced, it is possible to go to my Courtship and Marriage Guide to find the event and read the text to make certain...
Finally, like the certainty of 'taxes and death', there are only two events from which there is no return in FoMT/MFoMT and HM DS/HM Cute DS as far as marriage is concerned. The first is the Blue Feather Marriage Proposal Event. If your proposal of marriage is accepted, you WILL marry the bachelor or girl a week later. If a holiday intervenes, the wedding will occur the day after the Festival, but it will occur nonetheless. The other irrevocable event is the 4th Rival Heart Event for any couple. If you experience this event, the couple WILL marry a week later. No ifs, ands or buts...
What you can do, if you have reached your fourth year without marrying the girl or bachelor of your dreams, is this:
1. Make certain that you have the bachelor or girl that you wish to marry at deepest red heart level. You then CANNOT trigger the 4th Rival Heart Event;
2. Make certain that you avoid the location of the 4th Rival Heart Event until you have the girl or bachelor of your dreams at full red heart level. You can find detailed information about ALL Heart and Rival Heart Events in my Courtship and Marriage Guide. If you do trigger the event by accident, DON'T SAVE! Simply reload and avoid the event...