Hate when real life and things like work intrude on the more important aspects...
It is great she enjoyed the photo session! Great pics! Very important to keep her enjoyment and interest level up.
Does your wife have any sheer tops that she could wear for a photo session, when your friend comes over, or just going out and about [shopping, movies, whatever] and have the situation be more natural and casual? She could wear a shirt or front button sweater / jumper over the sheer top and leave the buttons undone, or open more as the time progresses. Would be less overt and she might feel more comfortable and be more willing to let others see her.