"No— no. You must've misheard what Watson said my dear." Sherlock said as he glared at his partner and turned to you. His girlfriend, yes. His girlfriend.

He asked you out not long ago (about 4months ago) and you two headed off well. He was in his study talking about a case—that involved his ex-fianceé, Irene. Who was also trying to get in contact in him for some obvious reason, either to solve the case or get a connection to get Sherlock back..that Watson overheard back in the doll museum. He and Watson immediately shut up when you came in, when you asked what they were talking about Watson's mouth slipped and said 'Sherlock's ex-fia—' which Sherlock immediately shut Watson up.

Sherlock never mentioned anything about Irene to you. He didn't think so,or crossed it in his mind but he didn't think it was necessary! You didn't have to know about how he broke off He and Irene's engagement on a damn letter— but anyways..that really didn't stop you from asking questions now.