The AHD traces the -lusion part back to the Latin ludere, to play. I would say that the word delusion in common usage, implies a certain fight against evidence to the contrary, which, as you have stated, is not really what you are looking for. Illusion on the other hand, to me does not strongly imply a falseness of the belief so much as a lack of supporting evidence without implying any ignored counterevidence.

Probably the idea that you define your terms is more important than finding an existing word that says exactly what you mean. If you want to coin a word I would suggest that it be based on the root -lusion, perhaps cupilusion from the Latin cupio, cupere to desire. Define it in the Introduction or Chapter 1 and go from there.