Or HaChaim on Genesis 38:2/אור החיים על בראשית ל״ח:ב׳

1 בת איש כנעני. the daughter of a Canaanite. The word "Canaanite" means a trader. Ibn Ezra writes that it is possible that the word Canaanite is to be understood in the usual way, i.e. a local inhabitant of the Canaanite tribes. I maintain that it is impossible to imagine that any of the sons of Jacob would intermarry with the Canaanites, something which their forefathers had so strenuously opposed, as pointed out specifically in Pessachim 50. The Torah was careful to say "the daughter of a Canaanite man," meaning that she herself was not a Canaanite woman. This is only possible if her father was a merchant, not an actual Canaanite. Had she been a Canaanite, Yehudah would have been guilty of a great misdemeanour by marrying her. If this had indeed been the case the Torah would have indicated it by writing "he married a Canaanite woman whose father was called Shua," or something similar. It would not even have required an additional word to inform us of that fact. The Torah should not have let us surmise that Yehudah married a Canaanite woman but should have spelled it out clearly.

2ויקחיה, he married her, etc. He performed all the necessary legal requirements for marriage.