Views sys.foreign_keys and sys.foreign_key_columns should give you FK details.
Also look at sys.dm_sql_referenced_entities and sys.dm_sql_referencing_entities.
For just any reference to another object, not for a defined relationship, try sys.sql_expression_dependencies. For example, if a stored proc SELECTs from a given table, that should be recorded in that view.
SQL DBA,SQL Server MVP(07, 08, 09) Prosecutor James Blackburn, in closing argument in the Fatal Vision murders trial: "If in the future, you should cry a tear, cry one for them [the murder victims]. If in the future, you should say a prayer, say one for them. And if in the future, you should light a candle, light one for them."