Can you afford to be jobless? Still with parents or a lot of savings?
Difficult to comment not knowing context, like is it girl you work with or girlfriend, but myself I never let job rule my life, I keep many strings to my bow to attain as much choice as possible if I need to bounce.
It may help you to be in a new environment, sometimes being in a particular place can be mentally draining and painful, it might do you some good being elsewhere. I think I've heard this story a bit from you and if this is the same girl, she doesn't seem worth the mental torture.
Having said that, I don't know anything about your situation and how swift a change can be to make on your part.
FFS man up lad. Why have I never heard of a girl quitting work over a bloke, unless she's being sexually harassed or whatever, in which case she takes the guy to court and it's all worth it in the end. This is mental.