Hi there!
The answer to this question isn't a perfect one, and I apologize if it is unclear.
Will, the main character, harbours romantic feelings for his friend Theo and can be romantic with other characters as well.
However, there is a very special and what I would consider "canon" route which leaves you in a platonic place with your previous love interests.
It is important that I warn you that this story is open about romantic and sexual relationships and depicts what it's like the be a young adult who is exploring the world of interpersonal relationships for the first time.
There is a long drinking game where characters speak about their relationships, sexualities, insecurities, and curiosities with their friends.
In the end, it is possible to finish things in a platonic way during several routes, but the themes that precede those endings could very well be uncomfy for aro/ace individuals.
The demo is a great example of what I mean about the discussion of sexual and romantic themes.
I'd love to send you a guide on how to achieve platonic endings privately if you do end up playing to prevent a negative experience!
We have a discord that is linked on this page, you can reach me there for a guide :)
There are also some in-depth reviews about the variety of endings, but they have a lot of story details, so I can send them if you don't mind spoilers.
Even if you don't end up finding Starlight Shores is right for you, I encourage you to keep exploring the indie visual novel community.
I'm certain there's a game you'll enjoy :)
I hope this helps!
-Sam