Do not understand. It is not about stories where the game leads us handily, and will not even allow us to continue the main story if we do not bring these "adventures" to the end. I mean completely optional side story, having a small connection to the main story, where MC's goal is to gain the feeling of a mature woman. Something similar to the stories of school friends but with a mature woman. A completely optional story but extensive. A story in which (if he manages to finish it) MC will get the feeling of a mature woman, not just fast sex.
I think the mc's pretty much 'feeling' about eight mature women right now.
But on a more serious note, i do get what you are trying to portray here.
if references to other games are allowed here;
i believe it would be more akin to what the MC will go through in trying to seduce the mother in "Man Of The House". Even with the built-in phone cheating app (beats messing around with renpy coding any day!), the MC will go through an extensive story-arc in convincing the mother.
It is similar in "Mother Seduction" where apart from the MC's experiences; player also gets to understand the inner feelings, turmoil and dilemma from the mothers' perspective regarding her son, the MC.
Lightly presented in "Milfy City" too. Not so much with the mother, but more so with the sisters, where the player will have to understand the respective sisters mood and feelings towards the Mc before choosing the appropriate dialogue careful not to mess the relationship built up so far.
"My Sweet Neighbors" is another where the MC will nail the neighbor easily enough, but if the player chooses to follow the neighbors daughters route as well, player will have to understand the daughters' feelings towards him to react appropriately.
but, if you are like me, you'd keep returning to SummerTime Saga for its easy and straight-forward replayability,
(oh, and the "fast-sex" too) and especially after every major update, just to unravel what new treasures the update has brought.
and the Saga continues...