There's not a lot of sex going on in Middlemarch. It is, after all, a Victorian novel, and the Victorians were all about repressing sexual desire. There is, however, a lot of jealousy and suspicion…and there's some grand passion and some pretty obvious sexual attraction. Also, Dorothea's sister, Celia, has a baby, and we all know where babies come from. So we're giving it a "PG" instead of a "G."