Sentence:  Ralph Wiggum is generally employed as a bottomless fount of glorious non sequiturs, but in “I Love Lisa” he stands in for every oblivious chump who ever <WSD>deluded</WSD> himself into thinking that with persistence, determination, and a pure heart he can win the girl of his dreams. 
Meaning of the word marked with <WSD> tags:  To deceive into believing something which is false; to lead into error; to dupe.