There is no one way to do poly. I certainly wouldn't treat you that way and I am as poly as they come. Its how she does things.
There is no reason why you should be not suitable for poly if its what works for you. Anyone who wants to be in a poly dynamic is appropriate for poly.
If poly works and you resonate with the theory of loving more than one with integrity, honest and open communication and considering partners when you think of where you are going in your life and with whom, then you are good to go in poly as far as I can see. If she is not fulfilling what you need in a partner, then maybe you need to get to the bottom of that.
It sounds rather odd that she would go to another man when you are in town and not be willing to plan dates when before she did. Is she starting a new relationship? Is she in NRE with them? Did you ever plan dates? Have you talked about what is going on between the two of you in terms of investment in one another? It sounds like you have a lot to talk about before jumping to conclusions. Have you asked her how she is doing in the relationship you have?
No assumptions and no expectations is a good motto for having poly relationships. If you don't know for sure, ask. If you expect something then let your partner know and find out. It has worked for me in getting to the bottom of things really fast. Maybe it will for you too.
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