The big rumour is that Vasseur, the team principal, and continuing managing director Cyril Abiteboul, clashed badly during Renault's first season after returning as a full works effort in 2016.
Vasseur has now told L'Equipe: "In the assessment of the first year, it appeared that there were serious differences in the management, and suddenly it was impossible to manage the team as I would have liked.
"But above all, it was detrimental to the overall team to have several leaders."
Many see Vasseur's exit as a big blow for Renault, so asked if the end of the relationship after just one year is a failure, the Frenchman was not sure.
"For Renault, I don't know. In my case, I cannot say that. It still remains positive," he said.
"I think we've done a good job rebuilding the chassis factory at Enstone. While all this work has not paid off yet, we feel that the team has progressed in terms of track operations.
"It's the same on the engine side. In Viry, they have also been able to advance the engine, which is encouraging. Failure, no. But frustration, yes."
Renault finished 2016 in ninth place in the constructors' standings with eight points.