unrealistic fantasy

空: sky, air, heaven

a unisex given name / 大翔: a male given name

空で: by heart, by rote

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

perfect, completed

completeness / perfection

(と〜) thinking that […] (with the next clause explaining that the truth is contrary to expectations)