I'm pretty sure thats impossible, you can propose in the actions menu but i dont think they can propose to you
Viewing post in The Spirits of Sabil (+18) comments
They can. It’s in one of the update posts, but you can test it out for yourself. In that same playthrough Sean confessed to me no problem. I think Ori's might be locked until you complete the Ku event, but I hope it isn’t event-locked since the idea that there needs to be a push for a confession would already be covered by the affection gain. At the very least it should be the event itself in which the confession takes place, rather than an event such as Ku's which has alternate dialogue depending on the player’s relationship with Ori.