You probably missed it. After having sex with a condom with your Holy mother for the first time, she suggests seeing your Lit teacher to discuss the sinful things you are doing. You have to talk to your teacher and arrange the sessions, once a week.
You probably want to start doing this as it leads to the teacher watching you have sex, with and without a condom, and a threesome with your teacher, Holy mother, and you. It is also required for you to have sex with the teacher, and another threesome with you, the teacher, and Lily.