The look on their face cracks me up - like they were caught doing something wrong!
I did let them out together last evening and they keep their distance.
I tried again tonight and, at first, kept a constant eye on them while they were at two total opposite sides of the room. Eventually, I started doing something else while giving them a look every so often. Eventually, this is the sight that met my eyes - they had very quietly got closer and had started preening each other.
This made me quite happy - seems like they remember that they used to do this!