It does make me wonder in a way if subaru's hallucinations of hina is just how he assures himself that she still "likes" him. (Disclaimer, i'm not denying that the poor guy clearly has ptsd from the event and this is just me playing around in the analysis). Because hina in their conflict resolution did end up admitting that she loves subaru when he "wasn't hers" as opposed to subaru "who doesn't have a girlfriend." hina doesn't explicitly mention that she wants subaru to stay forever single; she doesnt even imply it. If anything, she wants to go back to their relationship where she could feel the established boundary between fan and fave youtuber bc she's realized that her obsession terrifies subaru and makes him deeply unhappy. I think it goes by saying that as long as this boundary is "up", (ie. they're in different worlds and stuff and there's no way for them to meet/breach this barrier) hina would support subaru, regardless if he does find a hot idol gf as long as he seems to be sincerely in love with her and treasures her.
So subaru always reflecting back to the height of hina's obsession despite her confession (and genuine attempt to stay back, we didn't see even hina's silhouette in the fanfest im so sad 😭😭) to stop and respect subaru's boundaries even if it's already too late... makes me wonder if he's similarly hung up on this instance of her obsessively and seriously in love with him to reassure himself that she still likes him. He can't see hina, her activities are very quiet and lowkey, sometimes she doesnt even tweet, and the only way subaru can check if she's still there is if she comments on his livestreams, and he's already increased frequency of that one. What if hina stops supporting him? But there's no way she would—she tried to hit him with a hammer once because she loved him so much