(1) The aim of the present study was to evaluate and characterize changes in alcohol use during the COVID-19 confinement in a sample of Spanish adults, analyzing their age and living situation as defining life cycle variables. (2) Method: Data from 3779 individuals were collected through a set of online surveys. AUDIT-C was used to measure the frequency of consumption, the average daily consumption, intensive consumption, risky consumption, and Standard Drink Units. (3) Results: Although alcohol consumption during confinement showed a significant general decline, age revealed important differences, with the decline being more pronounced in adults from 18 to 29 years old. The living situation also showed significant differences. The largest decreases in alcohol consumption were found in those who lived with their parents or other relatives, whereas those who lived alone or with a partner even increased their level of consumption. In addition, the data show a significant interaction between these two variables and gender. (4) Conclusions: Age and cohabitation processes are key factors in understanding the life situation of each individual during confinement and, consequently, in explaining consumption patterns. The results obtained provide interesting recommendations for designing prevention policies in both normal and crisis circumstances, emphasizing the need to understand alcohol use from a psychosocial perspective.