When does a skirt or dress climb up? When it's too tight. Fabric gets stressed and wants to go somewhere more comfortable and usually that's up!
Why did I wear a tight dress today, since I knew what would happen? Well when I tried it on at the store I was on pants and I thought that with panty hoses it will fit smoother...but guess what, it didn't. I still like this dress too much not to wear it.
That's why it's a good thing to know how to sew. You make your own at custom fit, shape, colour etc. If you have some extra weight you don't feel at ease at the store, when clothes don't fit right and you don't mess up with your good mood. So go on and sew!
I wish I could fix it, but as every ready made apparel there is not enough seam allowances.
So in conclusion, bad choise of dress for this long difficult day. I'm going to spend the rest of it pulling it down...