He could just mean,"if you want to know why my love for you has lasted just take a good look at all we've done together". The willow blooms could be at a romantic place they visited together and the corners of each room could represent the life they have made for themselves. Those are things that just don't end overnight,so he's just re-affirming his love for her by saying that. Hope that makes sense. Borderstone,outta here and Alberta Bound!
