Ladies, I need some advice / opinions...
You left out a lot of pertinent info, like if you are staying in the same hotel room as your female friend, how long you have been dating your girlfriend, etc.
What it comes down to for me is that she is your girlfriend, not your fiance, not your wife. She really doesn't have much ground to stand on in having a say in what you do as you have not made a serious commitment to her.
That said, if my husband had done this to me while we were seriously dating but not yet engaged I would have had an issue with it. It's disrespectful to not discuss it with her before you purchased the tickets (or maybe you did?). Putting myself if your girlfriend's shoes for a moment, to me the issue would be about a lack of respect for my feelings. The fact that you got the tickets without discussing it with her means you didn't even consider how she might feel about it. GAF is fairly socially liberal but a lot of the "real world" is much more conservative and wouldn't be okay with opposite sex staying the the same hotel room when one or both parties is in a committed relationship.
If you see a future with your girlfriend (marriage or similar) then don't go, it's not worth it. If you don't think you will be together long term, do what you want.
Edit: Just read the update that your friend got the tickets, not you, so that's a bit different in that she asked you to go, not the other way around. Still, I hope you discussed going with your girlfriend before you committed to going with your friend.
Well, I trust her so I wouldn't really have issue with it; if it's an event that I didn't want to go to, then by all means if she was excited to go, then go.
Going to have to call you out on this one. It's not always about trust, it's about respect. Really it depends on your girlfriend's personality and previous life experiences but her issue may not be that she doesn't trust you, it's that she feels you don't respect her.
As always, try to talk it through.
Just got home from the bar. Long work day and wanted to cap it off with a nice drink. Some tall man tried to converse with me when it was clear I wanted to be alone after ordering my drink. He kept invading my space. He said that if Hillary wins that there will be World War III and that if Donald Trump wins we'll have a Civil War. I kept trying to signal to the bar tender to come and get my money so I could go, but he didn't come on over.This guy wouldn't leave me alone and I had to listen to him. He ended up talking about how his dad's birthday was on Friday, but that his dad died in 1998. It started to really, really scare me. He had scary eyes that looked like they were coming out of his skeleton. He said he was thankful I listened to and conversed with him but I really only did so because I was scared and he was invading my space. I was there alone and was completely on guard and this still happened. In the end, I tried paying for my drink (which I never left unattended thankfully) but he wanted to pay.
I swear if he was going to lay a finger on me I was fully prepared to put him in a rear naked choke in the middle of the bar.
I ended up having to look bar to see if he was following me or not when I left.
Did I overreact? Was he just trying to have a friendly conversation?
Dude was creeping, no doubt about it. If it was intentional or not makes no difference, end result is still the same. It really bothers me that in our society women are expected to be constantly contentious of how we come off to other people and make others feel but men are permitted to go around completely oblivious to how the are perceived by others. And if we women take offense to their off-putting behavior it's still somehow our fault for not "understanding" that they don't know any better.