Friends and Polyamory

Why is it so dificult to be friends with poly people? I guess it is because they are almost always available. I was getting to know this poly person and we're, in my eyes, becoming friends. I then get a text telling me that they are interested in me as more than friends (now just to clear things up, I am of the opinion that I am poly. I have however entered into an agreement with my wife to not enter into another relationship until she does. This is because it is percieved, and to an extent true, that in the past it has been easier for me to enter into another relationship.) to which I replied that although I am interested I have an agreement with my wife and that I'd love to remain friends. Since then they have avoided me like the plague with mayhaps a wave or a smile here or there. When confronted I was told that she was just giving my wife space, space I believe was not needed because we were all getting along just fine, and how long is this space meant to last as it has been atleast two months. So again I ask "Why is it so difficult to be friends with poly people?"