This paper examines the associations between timing, events, and nationalist sentiments among the mainland Chinese Weibo users toward Taiwan following the visit of Speaker Nancy Pelosi of the US House of Representatives on August 2, 2022. Utilizing a dataset of 4,353 Weibo comments and employing a combination of regression and interview analysis, our study has revealed several key findings: (1) Nationalist sentiments have diminished over time, and this can be attributed to an increasing immunity to Taiwan-related topics among netizens, habitual mood control, and the processing of new information. (2) Military action against Taiwanese separatists has the potential to intensify nationalist sentiments among the Chinese public, possibly due to its perceived efficacy in countering threats to the country’s sovereignty. (3) Military action’s positive association with nationalism tends to be amplified if this person is a male user. (4) Nationalist sentiments in response to political actions are more likely to diminish over time. (5) Nationalist sentiments in response to military actions tend to rise more slowly or diminish more quickly among those in the China’s Southeast (i.e., the provinces of Guangdong, Fujian, and Zhejiang). (6) The events after PLA’s military drills around Taiwan have a tendency to dampen nationalism whether people’s expectations for government action are fulfilled or not. This research supports the theories of inoculation, telic hedonism, and information utility in explaining the diminishing of nationalist sentiments among different groups. Furthermore, it validates and extends the EPPM in assessing how events interact with gender and regional factors to incite nationalist sentiments. Finally, this study highlights the potential for integrating reversal theory with Maslow’s theory of need to better understand reversals in nationalist sentiments.