What is the status of your relationship? Have you had a discussion regarding your commitment level? Does he refer to you as his GF? Have you all agreed to be exclusive with each other?
I'm not intimating that he is seeing other people I don't see any evidence of that. These are normal conversations a couple would have, and I am wondering if you have? The only thing I will say in his defense now that I think about it, is that I have known a FEW women with kids below 18 that have kept a distance to an extent with the person they are dating. They don't want to put their kids through 'losing" another person because they already have once in a divorce.
Here we have the actions to the positive with the words that aren't matching, its usually the other way around. I agree with Lilro I would take a step back. I do think a conversation is in order here clarifying where you both are at the commitment level, and where you see the relationship headed, inclusive of marriage (do you want to get remarried someday - does he?).