Bob is wrong in that it is not so common, but does happen from time to time. It is not so different to a member regular doing a similar thing. In my experience too much interference from well meaning others often throws the interested member out of the fantasy. This is what you are experiencing. You choose the model to be with, not someone else to be with. When a model gives over herself to someone else, it is the someone else you are with.
Usually you must move on sadly, no matter how much you like the model. For myself I have tried to ignore someone directing (not in chat but in an actual pvt), chasing only the physical part, but the director kept getting it wrong, assuming my taste for his own. I suspect it never works, significant others should offer other kinds of support. The involved models usually have partners who trust them to know what is best for their members.
No need reporting it, even though it is a bit of a scam (you are not interacting with the model)... it was not vindictive and only hurts the model in the end. What you experienced is pretty rare.
A warning, some models help each other with chat too, especially when their English is not so good. They tend to know the one they speak for better and don't try to read the member's fantasy, I guess because they are models.They usually make a model seem better than she actually is though.