Just FYI, some people don't consider skippable content optional, especially in instances where whenever you've skipped a scene there are still references to it having happened so that it's very clear that the content of the skipped scene is very much part of the story. This issue also becomes bigger as you increase the number of unavoidable LIs because the more content a player is skipping, the more the feeling grows that the game maybe just isn't for them. There's nothing inherently wrong with having unavoidable content, but in a sandbox style game, (which is meant to give the feeling of picking what you want to see) the more of the content is unavoidable the more tedious it feels.
I saw earlier in the thread that you said you made it a sandbox instead of a VN/KN because you're not confident in your writing. Imo, the same kind of filler content you would create to pad out the story and make the world fill less empty in a sandbox could be implemented in a VN/KN and be just as effective, and as a bonus you have tighter control over the flow of the narrative, so it's easier to avoid continuity issues and bugs, generally. I also think that some of the types of scenes/interactions you're currently thinking of as filler or padding are really one of the biggest draws for a lot of AVN players anyway. Even in a more traditional narrative structure, a VN would include a fair number of "padding" scenes to help provide emotional depth and weight to the more plot relevant and lewd scenes, and a lot of VN and even AVN fans really love the cute/awkward/sweet scenes that help you understand the characters better.
Imo this story would be better served as a VN or KN. So little of the content being avoidable makes the sandbox feel very tedious and unnecessary. It might help your confidence in writing to just write the main story by itself however you're doing it now, and then write the romantic (or any other not-directly-plot-related) scenes for each character separately and deciding where they fit into the story after everything is written. Alternatively, you could do the opposite, where you come up with the romantice scenes first then figure out how the overarching narrative flows around them as you write it.
If you're deadset on keeping the sandbox format, I'd recommend making all of the romantic content and as much of the rest of the content as possible completely optional and avoidable. I hope you're not getting the impression that I'm just trying to take a big dump all over your project. I think it's a very cute and cool idea, but I think the current format is doing a huge disservice to the content, as is. You also seem to maybe be worried about length, but I don't think you should. You just started. It'll definitely get longer as you release more updates

. The further you get into development though, the more difficult it will be to make sweeping changes to the format/presentation of the story that'll help it land best with its intended audience, and the more difficult it will be on that audience having to start over due to those changes. Whatever you decide to do, I hope your project is a success. It seems like a neat twist on these kinds of stories