We all do it. There are a lot of reasons why, but generally we play with our hair when we're feeling anxious or nervous — waiting for a job interview, standing near someone we like, or, for brides, waiting for the ceremony entrance moment.
Having your hair done professionally is something you invest real time and money into, and it's captured in your pictures forever. Touching and playing with it will make the hairstyle fall faster — but you can retrain the habit.
Start by noticing when and how you tend to touch your hair, then swap the movement for something gentler. Instead of running your fingers through a section, use your index finger and thumb to lightly massage the area with short movements. If your tic is tucking face-framing pieces behind your ears, try sliding just your fingertips around the ear instead of gathering all the loose hair at once.
Think of your hairstyle as a complete unit — decide where you want it to sit, and try to keep it there through the ceremony and reception. The less you touch it, the less friction and the less product gets removed by your hands, which keeps the style from getting weighed down. It takes a little conscious effort, but by your wedding day it'll be second nature — and you'll be glad you practiced when you look back at your photos.