Guys, guys, guys!
Danny De Vito directed a short movie about two grumpy old men in love and it's the most romantic thing ever.
Here you can watch it: https://vimeo.com/159449591 It's called "Curmudgeons" and it's about 15 minutes long. And it's great. If these two aren't Draco/Harry in all the goldenage, grumpy grandpas in love scenarios though!