Kouji is making sure we know these are Admibro's destroyers. The ones he married. And yet he won't marry Ooi.
That is... slightly inaccurate. From what I read, or should I say, infer, from Kitakami's explanation, it's more like it's Ooi who won't marry him. Of course, we haven't see Admibro's perspective on the whole thing so we don't exactly have full insight yet on the matter.