<p>People in romantic relationships commonly engage in sex not only to pursue their own pleasure but also to meet their partner’s sexual needs. Being motivated to meet a partner’s sexual needs has been shown to be beneficial for relationships. However, this benefit can be limited if it comes at the cost of people neglecting their own needs. In this context, the role of sexual assertiveness, as a component of sexual autonomy, may be crucial, as it reflects one’s ability to communicate sexual needs and to reject unwanted sexual acts. Across two studies conducted in China, including an individual study (<i>N</i> = 692) and a dyadic study (<i>N</i> = 470), we extended previous findings from Western research that sexual communal strength was generally associated with greater ego-centered and partner/activity-centered sexual satisfaction, while unmitigated sexual communion was associated with greater sexual distress. Importantly, people with higher levels of sexual communal strength exhibited higher communication assertiveness but lower refusal assertiveness, which was in turn linked to sexual well-being. In addition, those with higher levels of unmitigated sexual communion showed lower levels of both types of sexual assertiveness, resulting in greater distress. We also found some significant partner effects. Given the collectivist cultural context of China, where responsiveness to others is highly valued, our findings highlight the nuanced role of sexual assertiveness in shaping the relationship between sexual communal motivations and sexual well-being. Results highlight the importance of balancing sexual responsiveness to a partner with autonomy, contributing to more satisfying and fulfilling relationships.</p>