This article proposes a bidirectional feedback mechanism for consensus in group decision making (GDM) driven by the behavior of decision makers (DMs), which is discriminated with a flexible harmony degree as one of three possible states: (1) ‘tolerance behavior’; (2) ‘rationalist behavior’; and (3) ‘conflict behavior’. The first two states are possible to be resolved in the consensus reaching process with one round of feedback recommendations to the discordant DMs. However, in the conflict state, which implies the lack of harmony between the group aim of ‘consensus’ and the individual benefit, it is unreasonable to be resolved with only discordant DMs’ feedback recommendations, and concordant DMs are also expected to make concessions at some degree. To address this not so unusual research problem, a theoretical bidirectional feedback mechanism framework for consensus is developed. Firstly, a maximum consensus driven feedback model is proposed to resolve ‘conflict behavior’ between the concordant and discordant DMs. Secondly, a maximum harmony driven feedback model is activated to support the discordant DMs to reach the threshold values of group consensus. A numerical example is provided to illustrate and verify the proposed mechanism usefulness and how it compares against other existent feedback mechanisms in terms of the extent up to which DMs’ preferences are changed for reaching consensus. © 2021 Elsevier B.V.