I genuinely have to ask...is Jillian x Oliver Canon? Cuz i heard that hes supposed to be aroace and i dont wanna erase that by shipping them- 😓
So, yes, Oliver IS aroace, but!! Aroace people can still be in relationships!
I, myself, am aroace, and Oliver came to be because I wanted to give a backstory to my persona, and then he kind of became his own thing. Either way, I'm aroace and I have a partner. This doesn't mean I'm not aroace, but aroace is both an umbrella term and a spectrum!
Also, aroace people can want to be in relationships for other reasons besides love, but even then, they can just love their partner in a non-traditional way. For example, I love my partner, and I don't know if I like the sexual/romantic stuff within the relationship, but I don't mind doing them because it's them, and with that, I enjoy just having someone to be close to and that's how my relationship with my partner works. This isn't for everyone, though!!
Now, to officially answer your question; I don't mind if you ship Oliver and Jillian! The novel is essentially a big dark mystery romance because of their relationship. Just understand that Oliver is aroace in the sense that he is entirely asexual, but enjoys his relationship with Jillian because he doesn't understand what it means or how he feels about her. This also is mixed in with the fact that he has ASPD, and becaus of that his feelings would be unusual to most people.
Their relationship, however, is extremely toxic. Oliver hurts Jillian by leading her on and manipulating her. Jillian is a victim of abuse, and both parties are at fault because Jillian only wants to heal Oliver while Oliver doesn't know how to handle relationships.
If you do want to ship them, be my guest! I love them together despite all of this because I enjoy exploring very complex relationships! I actually have an alternate ending where Oliver was never caught and so he ends up with Jillian, but it ends up torturing him into suicide (this was called the good ending, by the way, lmao ToT).
Anyway! Sorry for the long rant, I just love my characters!! Thank you so much for your question, I hope I answered it well, and thank you for enjoying my story!