Why does it say "he fled and went outside" in Pasuk 12 and here, but in Pesukim 13 and 18 it says only "he fled"?
Seforno (on Pasuk 14): She began to scream because she thought that Yosef was running to report her; but when she saw that outside he did not run, as everybody else saw, 1 that is what she told them. However, when speaking with her husband, who had not been there, she reverted to her original story - that Yosef ran outside as well. 2
Why does the Torah record her words to the household? Surely they did not lie to Potifar, to say that Yosef did so to them!
Ha'Emek Davar (15,17): This helped bring about the result, with Hashgachah. The household did not accept her words, so she needed to tell a new story to her husband.