And now that I consider it, I think some of my frustration is from the sense that they don't just want a discussion, they want a conversation that seems to be a discussion but is actually reassurance about their choice.
And now that I've reframed "agreement" as "reassurance" that helps me decide how to respond. In some cases, reassurance is appropriate and needed, but sometimes it's counterproductive and a sign that there's anxiety that needs to be addressed in some other way