Background: Critical events in the second half of life, such as divorce, pose a significant threat to well-being. Individuals undergoing divorce often experience feelings of social loneliness and may benefit differently from available resources depending on how much time has passed since the event. Personality traits have been found to be related to adaptation, with particularly strong effects immediately after the critical event. Other resources, such as identity-stabilizing mechanisms (i.e., valued social groups and self-continuity), may play a role only later in adaptation. However, little is known about the benefits of these resources and their potentially time-dependent effects on social loneliness when one is overcoming later-life divorce. Objectives: This study investigates the role of psychological (e.g., personality, self-continuity, multiple important group memberships) and social resources (e.g., new partner, having someone to help deal with divorce) for social loneliness in two post-divorce phases, using a married group as the reference, controlling for sociodemographic aspects and health. Methods: A representative sample of 850 divorced (aged 40–79 years) and 869 married individuals (aged 40–78 years) living in Switzerland were compared, using multiple regression analyses. Results: Differential predictive patterns for social loneliness between the two divorced groups and the married group were observed. For the short-term divorced (up to 2 years after divorce), higher extroversion and agreeableness and lower neuroticism were associated with lower levels of loneliness. For the long-term divorced (2–5 years after divorce) and for those who remained married, extroversion was similarly important for loneliness. Additionally, higher levels of self-continuity and multiple group memberships predicted lower loneliness, but the short-term divorced did not benefit from them. Having someone to help overcome the divorce benefited members of both divorced groups. A new partner was related to less loneliness, but only in the long-term divorced group. Conclusions: Our findings demonstrate that the effects of psychological and social resources on social loneliness vary by adaptation phase. Although extroversion is beneficial for all divorced and married individuals, other personality traits play a more decisive role in the initial adaptation phase. Identity-promoting resources (i.e., multiple group memberships, perceived self-continuity) are beneficial only later in the adaptation process. To be successful, professional interventions must be tailored as needed.