In Fire Emblem Three Houses you can unlock the ability to have tea with students and other characters in the Monastery. This is an important activity as it raises your Charm stat. You can get tea in Fire Emblem Three Houses by completing a side mission, at which point you will have the ability to have tea parties with people.
Complete the Tea for Two side quest to unlock Tea Time
The mission you’re going to look out for is the Tea for Two side quest. In this quest, Ferdinand will give you an Elegant Tea Set and you’ll need to give that item to Lorenz. The quest is fairly straight forward. Collect the tea set from Ferdinand and then take it to Lorenz who can be found near the docks.
Once you’ve delivered the Elegant Tea Set to Lorenz you unlock the Tea Time mechanic in the Monastery. You will be able to have tea with other characters by inviting them in the Monastery or asking them for Tea on their birthday. This activity does cost an Activity Point during your Free Day, but it will raise charm and potentially develop romantic relationships.
During the Tea Time event you will need to select your parties favorite tea and then ask them questions about topics you think they will find interesting to get the max benefits from your time.