Mate choice and intrasexual mating competition are the processes that drive sexual selection and can be interrelated in multiple ways. Female preference may be altered by exposure to male–male interactions. This could happen because of a reduced ability of females to evaluate males in the presence of male–male competition or because females use information from male interactions to form mating preferences. In this study, female preference for a male tail ornament was measured in the presence and absence of male–male competition in a coral reef fish, the damselfish Chrysiptera cyanea. Despite the striking colors of coral reef fishes, few studies have investigated the role of their coloration in the context of sexual selection. When male–male interactions were prevented, females showed a temporal change in preference with respect to male tail coloration, preferring brightly colored males early in the study period and dull males later on. Thus, females did not become less selective but reversed their preference function within the breeding season. When males were allowed to interact, male–male agonistic interactions were extremely frequent and male courtship activity was strongly reduced. In this situation, females still displayed a sexual interest in males but were indiscriminate with regard to male tail coloration. Taken together, these results provide compelling evidence for plasticity of female mating preference, related to the social context and time in the breeding season.