The aim of this study is to explore the multidimensional relationships among factors influencing decision-making processes regarding women’s willingness to marry and childbirth in South Korea with recognizing the context of family development in East Asian cultures. To this end, we employed three different analytical approaches, including classification tree modeling, Cox proportional hazard modeling, and permutation feature importance evaluation. Leveraging longitudinal data specific to Korean women, we highlighted the significance of socio-economic factors in family development dynamics. Our findings revealed that financial stability played a crucial role. Unmarried women’s willingness to marry was influenced by their perspectives on economic stability, while households’ consumption capacity and financial capability determined childbirth decisions and timing. We observed a trend of postponed marriage among women in their marriageable age range, particularly those with stable economic situations, reflecting a prevalent trend of skepticism of marriage in Korean society. Additional findings related to values, cultural factors, and personal happiness also suggested the challenges that discourage younger generations from entering into marriage and starting families in South Korea. By offering insights into these dynamics, our study provides practical implications for addressing the obstacles faced, contributing to a better understanding of family development dynamics.