Despite being their teacher, they rarely treat Tamae like an adult. Even calling her Tama-chan.
In Volume 1 (or episode 2 of the anime), Shido had confessed to Tamae and wanted to marry her, though technically this was just practice as he was merely repeating what Reine Murasame instructed him to say. However, Tamae seemed to have taken this seriously and, despite their status as a teacher and student, seemed to have been willing to accept such a relationship; she went as far as to say, when Shido was legally able to marry, Tama-chan would be in her 30s along with saying "We'll have two kids: a boy and a girl, one year apart. Even after I quit my job, I don't want to change the person I am! I don't mind renting a home first, but it'd be nice if we could eventually remodel my house and have my parents live with us! Let's get married as soon as possible!"