Why does the Torah repeat the words "va'Yar Esav"?
Seforno (to 28: 6,8): He heard Yitzchak command Yaakov not to marry Benos Kena'an, yet did not realize his father's objection to all such women. Only when he saw that his own wives upset his father through their deeds, he married the daughter of his uncle Yishmael. This teaches us that Yitzchak could have objected to Esav's marriage to his Kena'ani wives.
Chochmah u'Musar (Vol. 2, p. 425): He saw that his father loved Yaakov more - even though Yaakov tricked him, he blessed him more, and commanded him about Benos Kena'an. Even so, Esav did not get angry at Yitzchak. Refer to 27:41:2:1*. (Malbim disagrees. 1 )
Ohr ha'Chayim: Esav sensed only that his father objects to them, but he was not bothered by their evil.
Ha'amek Davar: Even though Yitzchak did not command Esav about Benos Kena'an, he understood his father's desire, and fulfilled it (i.e. and married someone else), just like Yaakov fulfilled his father's desire to go to Lavan without a command. 2