That issue is irrelevant to our discussion.

His opinion is irrelevant to this issue.

In Marxism, it is said that the relations of production form the foundation of society.

They built a deep emotional bond before they had a physical relationship.

He is an expert in international relations.

His success had a cause-and-effect relationship with his efforts.

There is a complex love triangle between them.

This is the book that I am reading.

He and I are related by blood.

His claim does not match the actual relationship.