Texas Estates Code - EST § 751.132. Termination of Agent's Authority

(1) the principal revokes the authority;

(2) the agent dies, becomes incapacitated, is no longer qualified, or resigns;

(3) the agent's marriage to the principal is dissolved by court decree of divorce or annulment or is declared void by a court, unless the power of attorney otherwise provides; or

(4) the power of attorney terminates.