This reply is a bit late, but I hope you don't mind! As a self-shipper that's deep in the community, I can say that the large majority of us is aware that these characters are fictional and our relationships aren't "real". However, our feelings for these characters are real and usually as strong as the the feelings most people have for real people, which is why, as a coping mechanism, we say that they are our partners. It's not a hallucination because we know they aren't real and never will be and because we don't physically see , hear, feel, .. them in any way.
