Sentence 1: Gary had a big crush on Karen. 
 Sentence 3: One day, Gary decided to write out his feelings in a heartfelt letter 
 Sentence 4:  When he gave Karen the letter she was overwhelmed by emotion 
 Sentence 5:  To Gary's delight, Karen said that she felt the same way about him 
 Given Sentence 2: He tried flirting with her for years but she didn't seem to notice.