The adjective sprung, unlike (say) infatuated, does not normally take a complement; a person may be infatuated with someone, but is simply sprung. As with crazy or gaga, the target of the emotion is normally indicated by surrounding context; this is seen in the 1992 and 2003 quotations above. However, while relatively uncommon, it is possible for sprung to take a complement, construed with a preposition such as over (much like gaga); this is seen in the 2005 quotation above.