It's reasonable to expect that if a friend of yours wants to engage in physical contact with your boyfriend in your own house, she should ask you about it directly. Or at least mention that she proposed the idea to your boyfriend.
But it sounds like your friend has a totally different scale for "reasonable" behavior. I don't think she meant any harm by it.
You could let her know that it bothered you. But I wouldn't make too much of a big deal about it. I don't think she will understand why it bothered you, since she seems to be on a totally different planet in terms of how she relates to people physically & sexually.
It sounds like your boyfriend thinks she's rather silly. I wouldn't worry too much about this.
It also sounds like you're stressed out about the lack of time you have with your boyfriend. Any chance you could skip the poly weekends and have more one-on-one time with him?
Single, straight, female, solo, non-monogamous.