It's just that if you're going to insist on staying over, it'd still be rude to let you sleep somewhere that's super uncomfortable. [ don't think too much of it, not like she cares!! ]

But if you're fine with the couch, just use it. You can take my bed too if you want and then I'll sleep somewhere else, I don't care. Amakusa was always praising couches for being comfortable to sleep on either way.