Thor had not given Sif the whole tour, just part of it. Mostly, their walk had been slow as they caught up and discussed this and that, the island and home. He had tried his best to fill Sif in and assuage her concerns about Loki and, subsequently, Katherine. He did not want to be caught in this midst of a family feud again. Once had been enough.
There were far greater evils in the world than an adopted brother who had mended his ways. (At least, that was the thought Thor had!)
"Katherine! We are here!" he called in that boom of a voice, getting the door and holding it for Sif to enter the nice looking home.