My girlfriend often receives ambiguous messages from my boss, never answers his phone in front of me, and makes me believe them.

Frankly, you can talk to your girlfriend's boss directly. It's nothing. Some things can't be solved by a girl. Now that you've decided to deal with it, let's just say it. A competent leader will not harass his subordinates, nor will he mess around in the workplace when looking for a job. Only donkey eggs and horse eggs do this. This kind of person is timid and has no ability to spoil him.