This is unlocked during the first date with Saffron.
Early on in the date, she will bring up the fact that she is a vegan and ask what you eat. It doesn't matter what you say, so long as afterwards you say that you could agree to not eat meat around her. This will progress the date further, whereas picking the 'i eat what i want' option will end things early.
Shortly after this moment, she will notice your eyes wander around her flat and ask what you're looking at. Choose the pile of books, and then when she offers to read something from them, choose to hear a poem.