What does "throw the dog on the curb" mean?

This seems to be a mish-mash of the idioms Throw him out, Put the dog out, and Kick him to the curb, all filtered through the mind of Esther Perel. Ms Perel is fluent in English, and if you follow the link in the OP, I don't doubt you'll find her an engaging, even eloquent speaker. She was born in Belgium, went to school in Israel, and now lives and works in New York; accordingly her idiomatic usages are sometimes slightly unusual.

She means that Heather should terminate her relationship with Nick.