Joseph went into the house to do his business. . . and she caught him by his garment, saying, Lie with me: and he left his garment . . . and fled.
Frustrated that her continual pleading was falling on deaf ears, Potiphar’s wife finally physically grabs hold of Joseph to try to force him to have sex with her. But Joseph, not willing to even submit to force, does the only honorable thing to do - he gets out of the house as fast as he can. If you read the verses in their entirety, you will see that there was no one else in the house. Joseph could have had a relationship with his master’s wife and no one would have known. But God was watching and Joseph knew that. Therefore to honor God, he flees.