The purpose of this study was to investigate the association among relational boundaries with an ex-partner, social support and adjustment to a breakup among lesbian individuals. The participants, who identify as lesbian were assessed with Post-Breakup-Connectedness-Attitudes Scales, Scale of Social Support and Scale of breakup adjustment. After the pretest, 938 online questionnaires were collected in LGBT community and analyzed by descriptive statistics, one-way ANOVA, Person’s correlation and multiple regression. The results demonstrated that: (1) individuals who were not currently in a relationship, had a shorter time since the breakup, and negotiated the breakup were more likely to maintain contact with their ex-partner; (2) individuals aged over 20, with a longer dating time, more breakups, and currently in a relationship tended to have more social support; (3) individuals aged below 20, with a shorter dating time and fewer breakups, tended to feel more confused after a breakup; (4) individuals with more breakups, a longer time since the breakup, and currently in a relationship tended to have a positive adjustment after a breakup; (5) the more contact with ex-partner, the more likely it was to experience more pain, confuse, self-doubt, guilt and self-blame, while the less contact with ex-partner, the more likely it was to experience self-affirmation and to get through pain, to understand self-worth, and to return to normal life; (6) relational boundaries and social support among lesbians individuals significantly predicted breakup adjustment. Finally, suggestions for counselors and further researchers are offered.