Habit is a synonym of Use. Use is a synonym of Way. Way is a synonym of Approach. 
Mate is a synonym of Love. Love is related to Employ. Employ is the opposite of Fire. 
Habit <--Synonym--> Use <--Synonym--> Way <--Synonym--> Approach 
Mate <--Synonym--> Love <--RelatedTo--> Employ <--Antonym--> Fire 