Full membership in the European Union is something that Turkey wants to achieve. Conformity with Copenhagen Criteria is an obligation that must be fulfilled by EU candidate countries so that this has been pursued by Turkey since it first submitted a full membership proposal. The process of accession to candidate countries must go through the negotiation stage, which includes the conformity of 35 chapters of the acquis communautaire. In 2016 there was a change in Turkey's attitude towards the membership process in the European Union, so this paper discusses the reasons for the change in attitude using the Dual Concern Model Theory, Perceived Feasibility Perspective, and one of the alternative strategies in negotiation which is Best Alternative to a Negotiated Agreement (BATNA).