The authors propose a reciprocity-based theory to explain suicides associated with relationship problems. Employing a content analysis of suicide notes, the theory was tested. Evidence was found of exploitation, exploiter guilt, retaliation, & retreat as motives for relationship-based suicide. Reciprocity-based note writers were more likely to have used alcohol or drugs in the hours prior to their deaths, & they were also more likely to have made their intentions known beforehand. Implications for future research as well as for suicide prevention are discussed. (81 refs.)