HB 8/9: # Close, Party Invite, What now?

I was at a bar last night. Met a HB8/9 who managed to convince me not to leave the bar early so we could talk. Despite that, her interest level talking to me seemed to be slightly above neutral, occasionally looking around, occasional looking at her phone. We spoke for a while and then her friend and a guy named John showed up. John and HB greeted each other by touching each others waists, but beyond that there seemed to be little to no further kino between them. He firmly planted himself between me and her for the remainder of the night though, effectively displaying that this was his territory. My guess is that these two have been seeing each other for maybe a week or two.
The other problem is that they're both 25 and I'm 23.
So I was pretty much ready to leave when, lo and behold, she asks me what I'm doing sunday, telling me to come to her barbecue. We exchange numbers. I try to talk to her further but she gets disinterested again, and I leave. Suffice it to say I'm getting mixed signals.

So I plan to go, but what should I do there? Should I bring a female friend to Disarm John's suspicions while I work on HB? Or if I can't should I bring a wing? Should I spend more time trying to meet her friends etc? My goal is to pry these two apart (and I have no qualms doing so, the guy sucks) but I know not how.

Gimme your thoughts.