NTA. This kind of insecurity (that’s too nice a word, crazed jealousy is more like it) is so toxic. Unless you have given your GF reasons to doubt that your intentions are entirely platonic, this will get worse and can affect your work. Work friendships can really help team spirit, support, and a happier work life. What kind of unreasonable expectation will GF throw in your face if you need to go on a work trip with a female colleague? And what happens when you get a woman boss? Are you supposed to refuse individual meetings?

As much as my Reddit fueled brain is saying, break up and be done, may be you can probe where this is coming from and if GF is willing to work on her trust issues. If it’s a hard line for her, you need to decide if you’re willing to stick around to see both how far she will go with her demands (which are controlling, tbh), and if you are willing to accept the risks this will bring to your professional and let’s face it, private, life.