I don't really see the problem...? Reading everything you described, why would you immediately assume "foul play"? The proof for that is extremely thin. Sure, there might be a bit of innocent flirting/attraction etc going on but this is quite normal between men and women, at work f.e.

I hope you are not so tightly wound up that you don't allow her any breathing room when it comes to dealing with other men. Because this is asking for trouble, very suffocating to be in such a relationship, and insecure.

I suggest you simply loosen up a bit and don't try to control everything. If it is bound to happen it will happen anyway. Also, it would be very powerful to tell her: Don't worry, I'm fine with you flirting a bit and having fun with your colleagues, trust you completely to be responsible.

This is so much more powerful than distrust, if you want her to treat you and your relationship with respect. I mean, in the end what are you complaining about? All the attraction she might have for someone, she's throwing at YOU in the bedroom. How much more display of loyalty do you want?