Representation ends when the attorney files the lien and notifies the client of the statute of limitations.
Loyalty is the essential element in the lawyer's relationship to a client.
The requirement of loyalty dictates that a lawyer cannot simultaneously represent a client and act as his adversary, even in unrelated matters. But, assuming the partner may withdraw, it is not an ethical violation to refuse representation. A lawyer may refuse to represent a client unless ordered to do so by a tribunal. At some point, the representation must end. If the rule were otherwise, a lawyer would have to monitor a client's activities for the rest of the client's life.