Brad says meeting family & family is important yet....it appears that he met none of Emily's family except Ricki. & no explanation in the Episode unlike Melissa to Jason we had some reasoning given to the viewers. Strange indeed. Nope makes me go with Chantal.
A dr. asked me: Does anyone in your family suffer from mental illness? My answer: No they all enjoy it immensely.
Big: You know, Manhattan has a lot of beautiful women.
Carrie: What an amazing observation!
Big: But the thing is, after awhile, you just wanna be with the one who makes you laugh.
~ Sex and the City
I personally think it was Emily's to lose and between not staying the night with Brad (which they showed in the previews) + the whole 5 year old bit, it made him have some reservations. I think he wants a family but isn't quite ready to 100% settle down like he would need to do in order to be with Emily. I think him sitting down tonight, being scared to kiss Emily made him think that this is how it is going to be....and it would take some getting used to, for sure. So, I think that he started having reservations tonight and when she turns down the opportunity to stay the night together because "she is a Mom," it only magnifies it all.
Sometimes Emily needs to give a little bit more....and I think she really screws her chances of being F1 by not staying the night with him. You don't lose your morals as a Mom by staying the night with a man - she could have stayed and said, "Let's just enjoy each other's company until the wee hours and then I can go back to my room." Open up and experience this thing called life. And I think that Brad is terrified that she is going to be closed-off and that he will always play 2nd best to Ricki.