Question

I have a question,

So my partner was poly but decided to be monogamous with me. So now a few months go by and my partner is saying that would like to cuddle/watch movies and sleep with their friends platonicaly. I am against that because it seems to be a soft launch of a reintroduction of poly ideals. I’m looking for advice, I am against even the idea of that because cuddling and sleeping with other people feels like poly to me.