One central aspect that you need to focus on is the way that nature is treated in this excellent short story. Apart from the elements of the supernatural and the other aspectscommon to Romanticism, there is a definite theme of the natural world in this story. Rip van Winkle's "escape" from the crowded city into nature, where he experiences a massive life change, is a recurrent motif in Romanticism. It is the domestic strife that Rip suffers that drives him away from the town, the symbol of civilisation and stress, and into the woods, which Rip seems to do quite a bit. He clearly experiences peace and relief whilst "in nature" and contemplating its beauty:
From an opening between the trees he could overlook all the lower country for many a mile of rich woodland. He saw at a distance the lordly Hudson, far, far below him, moving on its silent but majestic course, with the reflection of a purple cloud or the sail of a lagging bark here and there sleeping on its glassy bosom, and at last losing itself in the blue highlands.
It is of course whilst in nature that Rip is called into the "wild, lonely and shagged" mountain glen where he experiences his prolonged sleep and repose, emerging into a very different world. Thus, the beauty of nature and how it provides succour to the soul, overwhelmed by the stresses and strains of life in the city, are key elements in Romantic fiction and this aspect is certainly to be found in this great short story.