Loneliness has been linked to many physical and mental health problems, especially during adolescence. From evolutionary, social needs, and cognitive approaches, this study examined whether emotional repair, relatedness need, and peer-rated indicators of relations behave in predicting loneliness, considering all approaches together. The sample consisted of 373 adolescents measured longitudinally at three time points. Results of a cross-lagged panel design found that, considering all the influences together, relatedness need showed the highest strength to predict loneliness. Furthermore, adolescents who were accepted by their peers and whose relatedness need was satisfied activated emotional regulation which additionally produced a decrease in prospective feelings of loneliness. In addition, loneliness has been shown to be a consequence of these variables.