What should I tell my niece who I recently found out is after a married man romantically?

I have no idea what to say to her. I'm ashamed she is my family. I'm even more ashamed my brother in law has raised a daughter who doesn't respect marriage.

So far, said married man is basically telling her he wants nothing to do with her. And is resisting, but she won't give up.
What should I tell my niece who I recently found out is after a married man romantically?
Post Opinion