Couples should value each other so much that they actually reverence each other, almost to the point that they could genuflect before their spouses. Because God dwells in their souls, we should treat our spouses as reverently as we do Christ in the tabernacle. Our Lord in the Eucharist is a gift to us and a means for our salvation. So, too, are our spouses, although not in the same form, ontologically speaking.
When we look at all the bright red hearts scattered everywhere we look, maybe we can think of the bright red heart of St. Valentine, who was martyred for the sake of the Bright Red Heart that was pierced for us on the Cross.