There are two basic types of Event in Rune Factory Frontier and in any Rune Factory game for that matter. There are the 'plot' or 'storyline' Events that are unlocked by your character's own actions, usually in the form of an achievement, whether it is a matter of tilling a specific field, planting a specific crop or defeating a specific Boss Monster. These Events allow the story to progress, unlocking new areas or new 'life' options for every one in the community.
The other type of Event actually consists of a number of different types of Events but all are distinguished by a Heart Level or Friendship Level Requirement. In other words, no matter how handy your character may be with a sword, however much money he has made or however many expansions he may have, the Event will not occur until a specific level of Love or Friendship has been attained either with a single individual or with every individual who is involved in the Event.
In the case of Rune Factory Frontier, there are a number of Events that are linked and could be considered a 'chain of Events'. The Quest for the Missing Scriptures is one of these. The 'Chain Events' usually are not Events that advance your prospect of marriage with a specific Eligible Girl directly but as they tend to require specific Heart Levels on the part of any Eligible Girls involved in them, they often will be triggered at the same time as romantic progress is made.
Note that in Rune Factory Frontier, you can give more than one 'Most Favourite Gift' on any occasion to boost Friendship Levels faster. You can give lesser favourites as well, but a second or additional less favourite gift will have no significant value in terms of raising Friendship Levels. Although a true 'Most Favourite Gift' will have less value as well as a second or subsequent Gift than it has as a first Gift, the value remains significant enough to make the effort worth your while in some circumstances. Note that the actual Love Level or Heart Level is affected only by the first gift of the day.
In the case of the Quest for the Missing Scriptures, if you fail to experience one link in the 'chain', increase Heart or Friendship Levels until the Event triggers.
Selphy will not 'confess' her irresponsible act to you, for example, until she has reached almost 6 Hearts. As with many Harvest Moon/Rune Factory games, the little Heart Icon that appears on the Relations Page is not the true determining factor where Events are concerned. Rather, it is a point total that the player cannot see.
In Harvest Moon DS/Cute DS, your character could equip a Love Bangle that would allow him/her to view precise point values of Love and Friendship. No such accessory exists in Rune Factory Frontier. The 'point' I am trying to make here is that you cannot rely completely on the number of 'Hearts' or 'Smiley Faces' on the Relations Page, although they give a fair indication of your progress with any character. With respect to Events, the trigger may be 'more' or 'less' than a full Heart.
In fact, it may be useful to note here that the Wedding Bouquet Recipe has a different point requirement than the ability to ask a girl on a date. 10 Hearts is 'maximum' heart level in terms of the Heart Icons, but when 10 Hearts is attained, the Love gauge will be empty still, signifying to the player that a higher level of affection can be achieved. At 8 Hearts, you should have the option of asking an Eligible Girl on a date. At this point, however, you will NOT be able to trigger the Wedding Bouquet Recipe Event with Stella. It is only when you have 10 Hearts AND the Love gauge is full that the Event with Stella can be experienced, placing you in possession of 'Happiness 101', the final Recipe Book.
All that aside, here is the complete Quest for the Scriptures in Rune Factory Frontier. This 'chain of Events' is interesting because it demonstrates that weather as well as the actual day of the week can be added requirements in Rune Factory Frontier as well, as it is in other Harvest Moon or Rune Factory games.
N.B. The Quest for the Missing Scriptures as well as the Wedding Bouquet Events are included now in my 2nd Year Walkthrough for Rune Factory Frontier. As with any Event or chain of Events that is predicated on Heart/Friendship Levels, you can experience these either earlier in the 1st year or later than the 2nd year, depending on your character's Friendship and Love Levels with the various participants.