I don't think we can compare a spousal relationship with everyone else either. Here's an analogy:
If your wife had had a baby before she met you and had put it up for adoption, would you be upset if she had never told you? You can compare this to a CDer who used to CD during his teenage years, stopped, and never told his wife.
But then if the wife re-established a relationship with the child; if, with the adoptive parents' blessing, she spent regular time with the child (several times per week) but hid her whereabouts from you for years and years, spent money on the child, looked forward to you going away on trips so that she could see her child and relished every moment when you were gone, etc, how would you feel?
I think it is a rare person who would not feel betrayed, who would not wonder why his wife did not trust him with that information and why she had been so afraid to say something, who would not wonder if there were other things the wife had not disclosed, and who would not question the very foundational trust of their marriage.