I can see why the story might feel this way early on, but from Act 3 most scenes are focused on the protagonist and the other characters also receive increased screentime.
If you're on the fence about RD, I'd recommend checking back after v0.12 which is where my vision for the game really starts to come together.
After the first optional sharing scene (v0.11), Valerie will come back home to tell the MC about it before beginning their training/fuck session. You can choose to take either a submissive or dominant role in this conversation, which will influence the direction of future scenes.
Being submissive here means that Valerie will tease the protagonist and take the lead during these scenes. If the MC is present, you will (usually) have the option to either join in or watch. Overall, there should be enough variance to tailor the route to your own preferences.