The failure of cross-border marriages has often been attributed to the large age discrepancy between husband and wife, while disadvantage resulted from the selectivity of husbands from low socioeconomic backgrounds has received less attention. Analyzing couple-level household survey data (N = 871) in Hong Kong, this study compares marital conflict in local and cross-border couples by examining the mediating factors such as age discrepancy and socioeconomic disadvantages. Our analysis suggests that cross-border marriages are subject to significantly more frequent marital conflict than local marriages. It also showed that an age discrepancy from 6 to 9 years (older husband) significantly increased the frequency of marital conflict. However, our analysis showed that counter to common assumptions, socioeconomic disadvantages—particularly the couple’s financial stress—instead of nonnormative age hypergamy explained the higher frequency of marital conflict in cross-border marriages.