Yes, s
Imagine they are dominos or Blacke Peter (children play it ... ). You can only play a card (or skill) with same colour - she likes money, you can play money. Some skills will have double or triple values, money-sexual. She will not accept sexual on its own, but will, with money. You are allowed 3 skills. 2 liked ones and 1 neutral - if its not in red field, you can play it, to teach her new skill.
It is bit difficult to understand in the beginning as there is no tracker of current builds.
Yes, there is a grind, or you can cheat all XP for player skills to 601, max is 640, but this will not trigger the skills, to avoid game breaking bugs or trigger bugs. Skill a bit grindy, to find all triggers, but ... up to you.
Baal7734 , Is there further progression from Over Affectionate Sister to Bartender Sister?
Would you mind to give a clues, how many different build there are per character, with a route for them?