As lifelong premature ejaculation (PE) and subjective PE are two different PE subtypes, the measurement of their characteristic features requires different objective measures. In this article, we address the differences between lifelong PE and subjective PE, in terms of the extent of variation of sexual performance and propose a new objective measure for research of subjective PE. By considering lifelong PE as a mainly "male" sex disorder and subjective PE as a mainly "man" sex disorder, we show that stopwatch-mediated intravaginal ejaculation latency time (IELT) measurement is most adequate for research of lifelong PE, but inadequate for research of subjective PE. Subjective PE needs another objective measure to capture its key characteristics. Arguments are provided to show that the characteristics of subjective PE are different from the key features of lifelong PE. The core issue in lifelong PE is the very short IELT with a very small variation in sexual performance. Subjective PE is characterized by a higher variation of sexual performance. Stopwatch-mediated IELT measurement is essential in case of small variation of sexual performance. In contrast, measurement of various parameters of penile intravaginal thrusting is suggested to be more appropriate in case of high variation of sexual performance observed in subjective PE. In conclusion, research of lifelong PE should be performed by stopwatch measurement of the IELT whereas research of subjective PE should be performed by movement tracker devices, designed to be bound to the males body and/or inserted into the women's vagina with robust software to measure intravaginal thrusting variation performance. Future studies are warranted to provide scientific data to support this hypothesis.