I'm sorry you (and he) are going through this.
I have no great insight but I think you were right to bring it up and put it out there - since it arose naturally out of conversation. BUT I don't think that he could possibly in a place where he has actually sorted out who and what he wants out of his life in the long-term. He just broke up 2 weeks ago - he is still in a period of grief and adjustment - and probably will be for quite some time. He may withdrawal from getting close to ANYBODY during this time period - because allowing someone to be THAT close opens you up to vulnerability and pain - which he has just suffered through.
I'm sorry you are feeling rejected, but my (amateur) advise is to just wait and see. Be the supportive friend that he needs - without pushing him too fast to commit to anything or make him make rash decisions in the face of his tumultuous feelings in this "freshly broken up" state. That what he can give, give what you feel comfortable giving and just ... breathe.
I may have missed it but, how long was he with this person? How long have the two of you been together in your current state?
Me: poly bi female, in an "open-but-not-looking" Vee-plus with -
MrS: hetero polyflexible male, live-in husband (23+ yrs)
Dude: hetero poly male, live-in boyfriend (4+ yrs) and MrS's best friend
Lotus: poly bi married female, "it's complicated" relationships with Dude/JaneQ/MrS (1+ years)
+ "others" = FBs, FWBs, lover-friends, platonic G/BFs, boytoys, etc.
My poly blogs here:
The Journey of JaneQSmythe
The Notebook of JaneQSmythe