I could not possibly give less of a how late my significant other stays out without me. Just so long as he or she keeps in touch so I know they're not dead in a ditch somewhere.
Curfews are for children, though. If I were dating someone who was uncomfortable with me staying out all hours of the night, I would want them to let me know and I would respect their feelings. But I can't imagine I'd take very well to being given a curfew. Unspoken expectations are dumb, too. Passive aggressive bull destined to create drama and resentment.