I don't think it's cool that the BM is so informal and intimate sounding with him. Meet ups to discuss the skids should be neutral and impersonal as much as possible. They are not social occasions like your BM seems to think. Your H needs to set a boundary with her so that she realizes that when he meets up with her, it is STRICTLY to discuss the skids and their welfare, not to spend time with her. Meeting at a park or in a coffee shop are better ideas and he should never let the BM buy him anything or accept gifts or treats from her. That crosses a boundary and turns the meets into something between the two of them rather than a neutral get together that's focused on the skids. Meals should never be involved with BM meet ups!!!! Meals are way too personal and date-like. I would throw the worlds biggest hissy fit if my H ever met up with the BM for a meal. Luckily, he detests even the sight of her and has good boundaries. When he meets up with her, I usually go along and if it is necessary that I not be there, he meets her in a local park at a picnic bench (no food involved!) or in a local coffee shop. Coffee is fine, but a meal is a big boundary no-no. He may have good mental boundaries and see the meal meet up as not a problem, but he is inadvertently sending the BM the message that he has a private relationship with HER rather than a co-parenting relationship, strictly relating to the skids. She is not his friend, lover, or wife. She is his ex and co-parent and that is it.

"If you want to tell people the truth, make them laugh, otherwise they will kill you." ~Oscar Wilde