Our TG Caption

... and you appear in another room, sitting on a couch with your girlfriend now sister. "What happened= Where are we?", you state with your newly girly voice. "I want a threesome with you, so I teleported us to the apartment of a guy I know" "What?, you were betraying me? I thought you love me?" "No wait! Don't get me wrong. I LOVE you, but I feel really attracted to this guy on a sexual level. But I don't love him. I would rather do dirty stuff to him. In the best case, with you together. Now be quite, here he comes!"

You try to get ready and act as female as possible, you don't want your mind to get changed afterall!