Re: Girl with dysfunctional BF stands me up. How do I react?
If you think she's worth it keep being friendly and inviting. If you don't just be friendly. Honestly it sounds like she's got a funny situation. One that shouldn't be you chasing her--if she wants something from you--be quick about your actions because she seems to be making this guy a priority in her life. So if se wants to have sex-make it easy where nothing can go wrong and everything happens sooner and faster and escalate early so she knows. By then its also up to her to not put you through pain and turmoil. You can play the victim if you want but its not going to do you any good. Same with freezing out. Sounds like she already stated the guy changed his mind about something and responded to it.
My opinion about what you should do is let her know that its not fair for you to be treated poorly. Acknowledge that she has a BF and they both have feelings but she should feel responsible tok for putting you into this situation with your own vulnerable feelings. If you do decide to talk to her about this be clear that it wasn't easy for you to open up to her because of your principles. If she discards it as if her relationship is more important to her than being an honest and respectful person them theres a really good chance shes not worth your time because she isnt respecting you.
If she continues to have a crappy relationship with that guy--let her chase you with apologies and preload her so she can work to qualify herself to you because she messed up. You have to give yourself some value here. Im not saying be mean or cruel to getting respect but she should know that you aren't just some other guy. You're not the one with forcing her into the situation.
Every moment counts, get out of your head and enjoy it.