<human>: Give me a shortened version of the text

I have altered the ages and names just to keep it a little more private. 

Basically I have been seeing Michelle for about 4 or 5 months now. We both work in a large grocery chain and she is the manager of a certain department and i am the manager of the store room. 

Outside of work we have a very healthy relationship. We just spent 5 nights in a row together which is our longest yet and it was really amazing.  When we argue we talk it out and put it all on the table. Our communication for the most part is really solid and outside of work I really adore her 24/7. 

However I struggle working with her. We don't have to communicate to much at work, but when she fails to do her job in a timely manner is causes me to fall behind too. I have tried to communicate with her in the past about certain things at work she could improve on and she has done the same thing but we always end up arguing. We both cant take constructive criticism from each other in a healthy professional way and I don't know why. Today was an example of when she really frustrated me. She has been falling behind this week because she has had a lot of work dumped on her. So i thought I would help her and make sure her department was running smoothly.  So i spent the first 4 hours of my day managing her staff. I did this to lighten her load so that she could focus on other tasks. After i finished helping her i noticed her not really doing any work. She came into the back of the store where i work and made a few personal phone calls and i just wanted to explode. She really does a lot right as a manager but there is just a few things that really make my job harder and it frustrates me. 

So my question is, how can i mention to her my frustrations with her work ethic without turning into a argument? Is there a way i can support her more without literally doing her job for her? And if there is anyone who has made a relationship work with someone they work with what are some tips?
<bot>: My girlfriend is a co worker. Sometimes she is lazy and it directly effects my work load. how can i mention to her my frustrations with her work ethic without turning into a argument?