Genesis 39:19

And when his master heard the words which his wife spake with him, saying, According to these things did thy servant to me, his wrath became strong.

AND IT CAME TO PASS, WHEN THE MASTER HEARD. She told him about it at the time of conjugal intimacy. Matters such as these did your servant to me, i.e., matters of intimacy such as these. So says Rashi.
So also did they say in Bereshith Rabbah: “Rabbi Abahu said, ‘She said it to him at the time of conjugal relations.’”
Now I wonder. Joseph’s master was a castrate, who had married his wife during his youth, and the Rabbis expounded, “ ‘Sris’ (a captain of) Pharaoh — this teaches us that he bought Joseph for carnal purposes only, but the Holy One, blessed be He, caused Joseph’s master to become castrated.”, the same word mentioned in the verse above. Moreover, how would she dare discredit herself and become loathsome in the eyes of her husband by telling him that she had committed adultery, whether by force or with acquiescence, which would have merited mortal punishment, for why did she not cry out at the outset, so that he should run away, as she did at the end? Now to the men of her house she said, He came unto me to lie with me, but not that he lay with her, only that he came to do so, but she cried out and he fled. And surely she would hide the matter from her husband. And should you say that she told him so in order that his anger be kindled against him and that he should kill him, [it would have been sufficient for this purpose that she say that he attempted to violate her, for] any servant that attempts to violate his master’s wife deserves the death penalty!
It is possible that they intended to explain the expression, Matters such as these, as meaning matters of intimacy, meaning, exposing and caressing but not actual intimacy, as his master had become physically castrate, having been visited by a disease which resulted in a lack of desire for conjugal relations, as is the case with a shachuf.
In line with the literal interpretation of Scripture there is no need for all this, for the Hebrew letter kaph, in the word kadvarim, is not for the purpose of expressing comparison to other matters. Instead its meaning is “these things.” A similar usage [of the letter kaph is found in these verses]: And she told her mother’s house ‘kadvarim ha’eileh’ (according to these words); And when he had spoken unto me ‘kadvarim ha’eileh’ (according to these words) I set my face toward the ground. There are many similar verses. It may be that the verse is saying that when his master heard his wife’s words which she told him — “Your servant did unto me such matters as these which I had immediately related to the men of the house” — then his anger was kindled.
It is possible that the kaph is here used for exaggeration, similar to its use in the verses: Why speaketh my lord ‘kadvarim ha’eileh’ (such words as these)? And there have befallen me such things as these (‘ka’eileh’)?
Now due to his master’s love for Joseph he did not kill him, or it was a miracle of G-d, or knowing Joseph’s righteousness, he doubted her words. Similarly the Rabbis said in Bereshith Rabbah: “The master said to Joseph, ‘I know this charge against you is false, but lest a stigma fall on my children, [I will put you in prison].’”

כדברים האלה, “things like this;” according to Rashi, Potiphar’s wife showed him how Joseph had tried to arouse her while she was in bed with her husband. This appears difficult, as Rabbi Moshe, quoting the Talmud in tractate Sotah, folio 13 pointed out that the name Potiphar is spelled in the Torah once as פוטיפר, (39,1) without the letter ע at the end, and on another occasion with that letter ע missing (37,36) The Talmud concludes that once he had become a eunuch, as a close servant of Pharaoh, he could not indulge in sexual activity, so that Rashi’s commentary seems forced, to say the least. In fact, it is suggested that he bought Joseph in order to indulge in homosexual relations with him. Alternately, his castration had only been a partial one. Ibn Ezra explains that there are indeed two types of castration. One is called a hot castration, the other a cold castration. [The term occurs in the Talmud Yevamot repeatedly, but I have not found it mentioned here by Ibn Ezra. Ed.] Medically speaking, someone who underwent the “cold castration” requires a great deal of heat before he can ejaculate any semen. Potiphar, according to this opinion, was afflicted with that type of castration.