Or HaChaim on Genesis 28:8/אור החיים על בראשית כ״ח:ח׳

1 וירא עשו כי רעות בנות כנען, Esau realised that the Canaanite daughters were displeasing in the eyes of his father. The Torah tells us here that Esau's only concern was the effect his Canaanite wives had on his father's sensibilities. The fact that these women were evil by nature did not bother him. His soul did not despise them. Subsequent events teach that the fact that Isaac disapproved of these women did not produce any results other than that Esau did not marry still more Canaanite girls. He did not consider divorcing these wives. Perhaps Esau's only concern was that his father's blessing would not be applicable to children born to him by his Canaanite wives, and that is why married a daughter of Ishmael to insure that his father's blessing would remain effective for his descendants.