Sex can be Painful. Sex is related to Affair. 
Trust is related to Loyalty. Loyalty is a synonym of Commitment. Commitment is a synonym of Liability. Liability is derived from Ability. 
Painful <--HasProperty-- Sex <--RelatedTo--> Affair 
Trust <--RelatedTo--> Loyalty <--Synonym--> Commitment <--Synonym--> Liability --DerivedFrom--> Ability 