Seforno (in 28: 6,8): He heard Yitzchak command Ya?akov not to marry the daughter of Cana'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 did he marry the daughter of his uncle Yishmael. This teaches us that Yitzchak could have objected to Eisav's marriage to his Cana'ani wives.

Chochmah u'Musar: Even though Eisav saw that his father loved Ya?akov more than him ? and even though Ya?akov tricked him, he blessed him more, and commanded him about the daughters of Cana'an, he did not get angry with him. Refer to 27:41:2:1*.

Ohr ha'Chayim: Eisav sensed only that his father objected to them, but he was not bothered by their evil.

Ha'amek Davar: Even though Yitzchak did not command Eisav not to marry the daughter of Cana'an, he understood his father's wishes and respected rhem - and married someone else, just like Ya?akov fulfilled his father's wishes to go to Lavan without a command. ¹