Help with open relationship "friends"

I sure do hope this gets through. And im allowed to post this. I've been dating my bf we will call him Craig for 7 months now. We have an open relationship. It's the first one of this kind for me.

He recently started talking to someone we will call them Jamie. Craig is really thinking Jamie is a good person and has potential good friend vibes. Craig enjoys talking to Jamie almost everyday since they first met they talk.

Craig is very interested in sleeping with Jamie. I raised concerns that this is past the open relationship "hook up" that is normally the deal. Im completely okay with the open relationship.

It has always been a hook-up and go maybe kept the door open for another time. But with Jamie, they talk every single day. I've read the messages it got to the point where I just couldn't handle the stress of always seeing a notification from Jamie on his phone.

It's been light with some flirtatious texts here and there. Craig did tell Jamie that him and I talked but and we decided it would not be a good thing for them to hookup because of my concerns. But the texting still continues and the flirting still continues.

Jamie seems more then comfortable with flirting with him still and he still flirts back with them as well.

Craig has said in his past monogamous relationship that his partner was always controlling with who he was allowed to talk to and that they didn't have sex for a long time and its because of that relationship that he is in open relationships. He cant be told what to do with his body. Or who he can and cannot be friends with.

I have brought up that some of his closest friends he doesn't talk to as much as it seems like he talks with Jamie. Is this normal in an open relationship? We have clear boundaries as to hooking up. No emotional or intimate sex just physical. We are completely honest with each other each time it happens before it happens and seeks approval before we hook up.

But this friendship/hookup has got all my flags going and im sitting on the bathroom floor 4 hours before I get up for work and I cant sleep.

He's done above and beyond trying to reassure me that its friendship and if sex is ever a thing it will just be the same as a hook up.

But is the constant talking creating a emotional connection? Is Jamie playing a long game trying to get him to become more interested in them?

Jamie is single and was engaged for 5 years and broke it off in December because the other cheated in their relationship. My pessimist side tells me it's a likely story. My optimist side tells me this is a sign that they won't intrude in my relationship. They also seem to not be into open relationships and that would never work with Craig. Im going crazy. I do feel like Craig loves me but if I dont get a handle on myself im going to come off as crazy if I dont stop.