Sudden is related to Danger. Danger is related to Worry. 
Lady is related to Person. Soldier is a type of Person. Soldier is related to Man. Boyfriend is a type of Man. 
Sudden <--RelatedTo--> Danger <--RelatedTo--> Worry 
Lady <--RelatedTo--> Person <--IsA-- Soldier <--RelatedTo--> Man <--IsA-- Boyfriend 