China's marriage registrations have declined dramatically, dropping from 13.47 million couples in 2013 to 6.1 million in 2024. Understanding public attitudes toward marriage requires examining not only emotional sentiment but also the moral reasoning underlying these evaluations. This study analyzed 219,358 marriage-related posts from two major Chinese social media platforms (Sina Weibo and Xiaohongshu) using large language model (LLM)-assisted content analysis. Drawing on Shweder's Big Three moral ethics framework, posts were coded for sentiment (positive, negative, neutral) and moral dimensions (Autonomy, Community, Divinity). Results revealed platform differences: Weibo discourse skewed positive, while Xiaohongshu was predominantly neutral. Most posts across both platforms lacked explicit moral framing. However, when moral ethics were invoked, significant associations with sentiment emerged. Posts invoking Autonomy ethics and Community ethics were predominantly negative, whereas Divinity-framed posts tended toward neutral or positive sentiment. These findings suggest that concerns about both personal autonomy constraints and communal obligations drive negative marriage attitudes in contemporary China. The study demonstrates LLMs' utility for scaling qualitative analysis and offers insights for developing culturally informed policies addressing marriage decline in Chinese contexts.

翻译：中国的婚姻登记数量急剧下降，从2013年的1347万对降至2024年的610万对。理解公众对婚姻的态度不仅需要考察情感倾向，还需探究这些评价背后的道德推理机制。本研究采用大语言模型辅助的内容分析方法，对中国两大社交媒体平台（新浪微博和小红书）的219,358条婚姻相关帖子进行了分析。基于Shweder的道德三原则理论框架，我们对帖子的情感倾向（积极、消极、中性）和道德维度（自主伦理、社群伦理、神圣伦理）进行了编码。结果显示平台差异显著：微博讨论偏向积极，而小红书以中性为主。两个平台的大部分帖子都缺乏明确的道德框架。然而，当涉及道德伦理时，情感倾向与道德维度呈现显著关联：援引自主伦理和社群伦理的帖子以消极倾向为主，而采用神圣伦理框架的帖子则倾向于中性或积极情感。这些发现表明，对个人自主权受限和社群义务的担忧共同驱动着当代中国对婚姻的消极态度。本研究证明了大语言模型在扩展定性分析规模方面的实用性，并为制定符合文化语境的婚姻衰退应对政策提供了理论依据。