I think Grant Gustin mentioned that when she comes to town she knows more about Barry's situation than Barry thinks she does, so yeah I think Oliver ends up telling her about it. Before I thought the date was Felicity or Barry's idea since the last time they talked they mentioned a date, but yeah, now I'm thinking that Felicity just comes to Central to check in on him and to visit as a friend and Iris tries to set the two of them up.