Accusing one’s partner of infidelity is one of the major causes stated by offenders when intimate partner homicide occurs. Much research has been undertaken concerning this issue among western research literature, but most of them lacked cultural considerations with respect to the psychological process of homicide. In Taiwan, researchers who investigated this topic with Chinese cultural consideration undertook only narrative research based on a single participant, which only presented the specific experience from an individual’s perspective and thus generalization is limited. Therefore, there is a gap within the literature on this this topic area. This study is based on Chinese Relationalism perspectives and is designed to comprehensively construct the psychological mechanism behind this type of homicide. Participants of this study consisted of ten male prisoners who accused their partners of infidelity and were convicted of homicide. Consensual qualitative research (CQR) was applied to analyze interview scripts, along with consulting written verdicts, criminal records, and records maintained by social workers. The results revealed one characteristics category and four process categories. The former was “Personal thoughts: Male thinking related to fidelity based on Chinese Relationalism”. The later includes (a) Fundamental reasons: couple conflicts along with the loss of role understanding; (b); Proximate reasons: the emergence of hostility after losing trust; (c) Explosion: the worsening of intimate partner violence and accumulated rage leading to intimate homicide. (d) Looking back: regret. There were several implications from these results. Firstly, based on Chinese Relationalism, the interviewees’ homicide process seemed to be “a deterioration process resulting from the loss of role understanding to the emergence of hostility.” Secondly, based on the results, it could be hypothesized that “during the process of intimate partner homicide, the loss of trust and the emergence of hostility caused by partner infidelity might be an important reason for the worsening of intimate partner violence.” However, no research literature has discussed the role of the trust/hostile related to the intimate partner homicide caused by accusation of infidelity; thus, this would be an important area for future research to explore.