Maybe I am off the wall, but I would seriously be questioning her motives and her personality. This throws up a few different types of red flags
First STD's protection? Seriously, I hope she is staying protected and you are protecting yourself from her.
Why is she rolling through men like this? Self-Esteem build up? Is she looking at this like a kid with a new toy? Sexual freedom while remaining with someone stable being that new toy... I am not against casual sex. I don't take part myself but I have no issues with other people doing it. Swinging, fucking for sport... whatever. But.. she does seem to be moving at a high pace with little concern for who she affects (including herself)
It sounds like you are the one she can be stable with. Move in with when needed. Do you provide her other means to?... while she goes out and has her fun. Call me a cynic, I don't see a whole lot of poly or even good relationship building in this.
The more I type the more negatively I feel about this. Sorry I don't see much positive in this.
what you call jealousy could be something as simple as feeling betrayed or even walked on... negative feelings can sometimes mix together like a cake mix.