I need some advice with this one:
A friend of mine and I occasionally go out to lunch together, and we always take turns to pay. A third co-worker sometimes comes along and she never offers to pay, not even cover her own lunch, and I am fed up covering for her when I know she never returns the favor. She is equally greedy at other occasions, eg. paying for coffee, rides etc. I am already dreading our next lunch, as I know she will come along again and it's my turn to pay. How can I avoid covering her part again without being too harsh (we have to work together closely at work, so I don't want her to turn against me). Any advice please?