Girlfriend is a type of Lover. Boyfriend is a type of Lover. Boyfriend is a different concept from Enemy. 
Sweat is related to Blood. Blood is related to Daughter. Daughter is related to Tie. Tie is related to Hold. 
Girlfriend --IsA--> Lover <--IsA-- Boyfriend <--DistinctFrom--> Enemy 
Sweat <--RelatedTo--> Blood <--RelatedTo--> Daughter <--RelatedTo--> Tie <--RelatedTo--> Hold 