This paper analyzes the effect of the COVID-19 pandemic on the within-household gender gap in relation to paid work hours in full-time employed heterosexual couples in Spain. Using the Spanish Labor Force Survey (2019–2020) and a difference-in-differences method, we analyze three stages of the pandemic: strict lockdown, de-escalation, and partial closures to study the short-term effects and potential medium-term effects on gender inequality in terms of paid work hours. Our results suggest that during the strict lockdown period there was a tendency to fall back on traditional family gendered patterns to manage the work–life balance, especially when young children are present in male-headed households. However, this phenomenon seems to be a short-term consequence of the pandemic. The sector of activity (essential or non-essential) has also played a key role, the gender gap increased in male-headed households with female partners employed in non-essential sectors.