This paper examines predictors of how people react when their partners change. People who feel confused about who they are tend to undermine their partner's changes, with downstream relationship quality implications.
Emery, L. F., Gardner, W. L., Finkel, E. J., & Carswell, K. L. (in press). “You’ve changed”: Low self-concept clarity predicts lack of support for partner change. Personality and Social Psychology Bulletin.