If I worked somewhere and my boss asked me how I did such a good job I'd fucking quit!

It would depend on what the attitude was:  Accusatory or complimentary.  If the g/f is upset, I doubt if the session was complimentary, and focused on her accounting for all claimed sales, etc.  Remember, we are talking a female-run workplace.  I have been exposed to a few estrogen-fueled workplaces, and the backbiting can be incredible.  Some fantastic people, and some real A#1 assholes.

Of course, I have done the interrogating many times as a fraud investigator, but only twice as a pleased manager.

With all the frauds, I never brought them into the office until I had everything needed for a conviction, including CCTV footage, marked bills, register receipts, etc.  100% confession rate, out of 75 offenders.  Employee defalcation and theft are no joke:  In every retail store, about 10% of people in the store at any one time are thieves, and half of those are employees.

The 2 people I questioned about their way of doing things both got bonuses and public recognition.

I hope your girlfriend feels better, knows she is doing a good job, and gets a raise and/or a bonus.

My wife had the same issue in her current company.  It is a regional discount real estate firm.  Their entire business is built on the listings.  My wife has a sales background.  She found that most realtors do not.  The company has asked her to conduct sales training classes for the company.  She has two years experience in the industry and is outselling by 2 to 1 people with 20+ years experience.  Last year, she listed 88 houses and of those 50 have already sold.  In addition she sold an additional 15 houses to buyers that she found.  
( most realtors are lucky to sell 5 to 10 houses per year )

She is the top producer in the company.  I know the other agents are flabbergasted.  I know they resent the " training " even though everything she tells them is the right thing to do and works.  Little things like follow up phone calls, being pleasent on the phone and letting the customer know that you are trying to help them and how, go a long way.  Its all about finding out what the customer wants and finding the best way to deliver it to them.

As to the bosses?  They love her.  They want everyone to be like her and they listen when she talks.  She has caused the change of numerous company procedures  that may work in traditional real estate firms but are a hinderence in their business model.  Little things like not having realtors on the floor answering phones when a $10 an hour receptionist could direct the calls.  The sales force needs to be meeting clients, not gabbing in the office.  Thats what cell phones are for.  Stuff like that goes a long way to enhancing productivity.

The net result is that not only are the co workers sometimes mad until they see the increase in pay, the competitors are perfectly livid because it has completely changed the nature of the business in our area.