Need help! Sex life of a extra

Okay ladies so my partner wanted to talk about trying new things. I'm thinking toys or something down that lane. NO... Totally opposite from toys.
He said he wants to have a 3sum his friend from work was talking about it and other stuff and now it gots him curious! I'm like 😂 your funny. Then I realized he really serious😰.  Now I told him no and he brought it up again. 
He even tried to say she won't have to join she can just watch.  He wants to see what his friend was talking about. How do I go about this.
 I even switched it around on him about so if I say I want a 3sum with a man or he can just watch your okay with it? He said no I don't want another man look at you doing anything. I said that's how I feel. 
So ladies what else can I do about this? 

Glow Resources

Let’s Glow

Glow is here for you on your path to pregnancy

Glow helps you navigate your fertility journey with smart tools, personalized insights, and guidance from medical experts who understand what matters most.

25+ million

Users

4.8 stars

200k+ app ratings

20+

Medical advisors