Oh oh oh! It is SO beautiful, and looks so lovely on you. Also, like Thistle, I fully support wearing a beautiful silk maxi dress for sitting on the couch (maybe a fainting couch/chaise longue!) and reading a book. So much better for one's morale than sitting on the couch in sweatpants. Need is... relative. Does wearing it make you feel gorgeous?
And yes, couldn't you wear it to... an outdoor wedding? A summer evening concert? Host a salon and serve champagne just to give you an opportunity to wear it?
I am the wrong person to ask if what you want is to be discouraged from buying it, and exactly the right person if you want encouragement and reasons to indulge. I recently ordered an absurdly expensive dress from Nordstrom "just to try on" and then fell in love with it and couldn't part with it. That said, the strategy of leaving it behind and then seeing if you still want it a few days later is always a sensible one. And Sundance... you can so often get their stuff on sale. Are you on their email mailing list? Cuz they might be offering some Labor Day specials...
