To feel this isn’t appropriate?

[Acrosstheseas]

I was speaking to someone I don’t know very well, only an acquaintance. But she shocked me when she told me this.
She said her and her husband have a girlfriend they share and they’ve explained to their young children that some relationships include more than 2 people…

I’m trying hard not to be judgemental, but does anyone else find this inappropriate?

What would you suggest they do instead? How should they explain who this person is?

Modelling good communication, openness and honesty is the best approach, and yes that involves parents sharing their relationship status.

(Which, incidentally, is not the same as sharing a 'sexual preference' or sharing that they are 'having threesomes' - I don't understand where that has come from. That is like saying that if someone shares that they are gay they are sharing graphic detail about anal sex. FGS.)