When an adult is vaccinated but their partner is not, there is a risk of the unvaccinated person getting infected and potentially spreading the virus to others. The goal of vaccination is to prevent severe complications from COVID-19, but it is not 100% effective. Even vaccinated individuals can still be infected, although the likelihood is lower. It is important to remember that vaccination not only protects the individual but also helps prevent the spread of the virus to others. It is recommended to continue practicing safety measures, such as wearing masks in certain situations where distance cannot be maintained. Stay informed and feel free to ask if you have any more questions.