Are divorce lawyers emotionally involved with their clients?

Are divorce lawyers ever getting involved with their clients? This question is not so nonsensical, as you may think...
This question has crossed my mind, when observing how my sister was interacting with her divorce attorney. They met first time in his Atlanta office when he was filling the separation papers. Some 20 months later, he's heading her divorce team.

Just looking at them together, you'd have thought they're a couple. It's almost as if the attorney has stepped into her former husband's shoes. She must like him very much; he makes very intimate gestures. It seems that their relationship has eveolved far behind the professional zone.

It causes me grief, because I don't want see her get hurt. As far as I know, she pays him the standard legal fees, with no "discounts" applicable. She has hosted him once in her marital home, only for an evening meal, as she admitted.
Anyway, a question arises: are legal practitioners, divorce clients or not, allowed to get emotionally close and eventually intimate with their clients? That would surely have a negative effect on their conduct.