I think if Armand could be completely honest, like stoned out of his many masks, he'd declare his love with something horribly bloody and darkly romantic like:
"I feel like I want to rip open your chest, right here in the middle, cut it all the way to the sternum and lift the skin until I can see your precious heart beating in its white, bloody cage. And climb between your ribs, next to your heart, to always feel its beat next to mine, the warmth of your blood warming my body. Then you'd always carry me with you, wherever you went, we wouldn't be separated, and you'd always be mine ❤."