Hi, do you recall what your wife liked to eat in the past? Sometimes as we get older our appetites get smaller as do our frames. I remember before my dad passed away at 86 a used to be tall man at 6'4 he shrunk down to 5'8 and seemed to small to me. He went off so many foods but enjoyed fresh fruits and peanut butter, well that is what he got
Your wife maybe going through the same thing and he started not liking food around 72. If he didn't get demsia and severe arthritis from head to to he would have lived as long as my zaida over 90...
Try this slowly at first cutting up the pieces then adding more different fruit she used to like, there is nothing as good as a fruit salad and very healthy.
The very best of luck