Sounds like he is caught in an "NRE syndrome" (New Relationship Energy.) Perhaps you're on different pages as far as appreciating different kinds of relationships (e.g. both shiny/new and tried/true).
Just make sure you give it ample time/thought (which you seem to already be doing) before making a decision on this one. It's a huge decision.
Love means never having to say, "Put down that meat cleaver!"