I'm going to hang out with office colleagues instead of going out with my girlfriend
Why would you want to hang out with colleagues instead of going out with your girlfriend?
I get to work with them a lot, so I'm more comfortable around them than her.
Rather than spend all your time with coworkers you need to spend more time with your girlfriend and get to know her, or else you should break up with her if you can't handle that
Fuck you man...
It's great that you are comfortable with your coworkers. But, what's the point in having a girlfriend if you never want to spend time with her? Talk to her, you may both be feeling the same awkwardness.