I figured out what's been bothering me...
He is less then a year out of a 4 year relationship. For her, he moved half way around the country to start a new life together, only to be dumped before he'd even finished moving them in.
I know I'm ready for a commitment. But I'm afraid that I am a rebound... Not that I have a problem with it. Only that (1) I don't want to plan a wedding to have it fall apart because he's ready to move into a "real" relationship, and (2) I don't want him to feel trapped by marriage (and/or a baby) when/if he knows it's time to move on.
We still need to talk out details. We did talk last night... He said, (for all intents and purposes), yes.