It is just the way it works. When people don`t have the feelings, emotional response, or experiences,..they go negative. We all do it at some level. Times where we see certain people, and based on experience think,..'This can`t work'.
It doesn`t matter if you are poly or not, 'This is a dating issue' as someone I know would say.
Some traditionalists will poo-poo anything alternative, and I`ve seen many a poly people say 'leave her/him' to others, or 'move on' or 'this cant work'......
Along with judgement, we all have our own motives for doing the things we do, and saying the things we say. Many times, bias exsists.
The proof is always in the pudding.
So,..just live your life, and if the negativity is to much,..remind people that if ' they dont have something nice to say, dont say it at all.
' Thats a old saying even traditionalists understand.
Also,..you and your new bf, plus your ex, might want to discuss not sharing the hearsay-negativity everytime. So if you are hanging around, and laughing about it, and swapping stories,..great.
Though, if you find that you are dwelling that the new bf`s friend made a comment like she did, you may just want to ask the new bf to curtail that type of info. Not forever, not always, but maybe in the meantime while you might be feeling overwhelmed.