After watching a Discovery prog on the Stevensons engineering and literary dynasty (had not realised R.L. Stevenson was part of the family). I ordered two books:
1) The Light House Stevensons from the library .. cost .. nothing
2) Classic FM Hall of Fame for my wife from Amazon...cost £12.83. (Classic FM had been promoting ex Waterstones for discounted price of £15 from £25).
Mine was scientific and cost nothing, my wives was artistic and cost £12.83.
You say that you ordered the two books so we can't draw any conclusion about your wife's character. (I presume you only have one wife so I'm going for the singular with an apostophe but I'm open to correction.) All we know is your assumption of what you think she would like. In my own, limited, experience husbands are seldom good judges of their wives' preferences in anything.
We can conclude that you are more willing to spend money on her than on yourself so, even if your judgement turns out to be a little faulty, it still shows that you care and she will love the book, just because you bought it.
"you are more willing to spend money on her than on yourself "
My wife was very pleased with your comment and assured me it was true. I would reply has always been so from time immemorial.
johnep