Except I am saying that grind is the result of a developer not being able to come up with a valid reason why your two characters would want to fuck one another. Moving away from this game Lets look at a game that I think did exactly what Faerin is trying to, but better. The game is View of Family. First off, I very much prefer his renders, secondly, I find what grind he has to be manageable.
In it, you have the exact same premise with little sister, only its well written. To start, you are a tutor by trade, that's literally what you do for a living. Second, you learn from your little sister that she's having trouble in school. You learn that she thinks the teacher doesn't like her, so she doesn't think studying will even help. So you go to the school. You meet the teacher and coincidence of all coincidences she's the teacher who you were fucking in high school.So you fuck her and blackmail her into giving your sister an A. However, you're seen by your little sister, she watches you, she even masturbates. So you confront her about this, naturally, and the idea of you teaching her about sex comes up. You agree, but on one condition, if she wants you to teach her about sex, she needs to agree to earn it by studying.
You tutor her for 3 days and by the end you decide to reward her with her first lesson. This goes on like this, a few days of tutoring and a new lesson. Yes, you're grinding by having to tutor your sister, but as I said before when I offered a fix to faerins' game, its not unheard of or unrealistic for a big brother to take time out of his day to help his little sibling study, and that is especially true if said brother is a tutor by trade. That said, this isn't your only interaction with her. You can also meet her on the beach every day at 17:00 where there are scenes that both advance the story and provide character development, while also giving you a repeated sexual encounter. You can find her in the living room every day between 18:00 and 20:00 where you, if you've gotten your relationship high enough can get a sneaky handjob twice a day, one of those while mom is in the room on the other couch.
Eventually you go to your room at the end of the day and find her asleep there. She wakes up and asks you to let her stay, so you do. You wake up in the middle of the night though to find her playing with your dick. All of this feels earned, the grind feels like the natural way your day might progress, and the interaction and story come to a climax to make it feel right, special even.
That doesn't even begin to touch the mom story line, which blows what Faerin does out of the water, in spite of, again using similar themes. In this line the psychiatrist mother of one of your students actually helps you in your quest to get your mother comfortable with her feeling for you, feelings which have everything to do with who you are, and not the fact that she saw you have a big dick. She doesn't fall for you because she needs sex, she falls for you because she's vulnerable after the divorce and you are there to support her, to become the Man of the House that she needs. I won't spoil it, by giving as much detail as I did the little sister line, because if you haven't you should play it. This game is far behind MotH in terms of development, but I think it shows exactly what this format is capable of when done correctly.