Odd to answer one's own question, but for whomever might benefit I'll post this follow-up.

DH was in a good mood last night, so it was a good time for a discussion. I noted that we both fear abandonment in one way or another. He agreed. I noted our frequent pattern. He agreed. I asked if possibly the reason that he threatens to leave is to get me to show how much I need him so that he won't feel so afraid. He acknowledged that was likely behind his actions. We agreed to work on that issue.

Progress.

Cowgirl