Separate is related to Other. Other is related to Partner. Partner is related to Relationship. Romance is a type of Relationship. 
Circumstance is related to Happen. Trip can cause/lead to Happen. Trip is related to Holiday. Holiday is related to Day. 
Separate <--RelatedTo--> Other <--RelatedTo--> Partner <--RelatedTo--> Relationship <--IsA-- Romance 
Circumstance <--RelatedTo--> Happen <--Causes-- Trip <--RelatedTo--> Holiday <--RelatedTo--> Day 