I would take the sign that he originally posted about you and poly in his profile to mean you are important to him. We all know how many men feel like they are a pariah to most all women if they say they are non monogamous - it doesn't sit right with me to say single either, but I can certainly understand it on an intellectual level.
Have you thought of discussing with him about if he's going to be open to introducing you to people he dates if he likes them enough to date them for a certain time? I think for me being open to that (whether or not it happens) would be enough to make me shake the feelings. Have you considered if there are any other things going on that make you wonder if he's not committed? Has he told you he is (or has he not, and so you being clear to yourself you are committed to him make you feel it might be a bit imbalanced?) Does he show you your importance in other ways like how he treats you around friends or family or are there other things he does to make you feel valued that you might be overlooking because of your feelings about the OKC profile? Don't worry, not expecting answers, just throwing out some food for thought!
Happiness will never come to those who fail to appreciate what they already have.