The stuff I consider romantic is probably dull to others, but I just like thoughtfulness.
I have a hooded sweatshirt that I swiped from my husband when we first started dating. I wore it all the time in college and eventually it became the first thing I'd put on when I'd come home from work and change, and seven years later it was falling to pieces all over the place. I mean we're talking holes in this thing. And I definitely was not attractive in it so I thought my husband would rejoice when I finally had to get rid of it.
Apparently he had been searching online to find another one and when he couldn't, he went to a website where you can design your own hoodies. He picked the same colors, matched the lettering style, and even measured out the sizes. I came home one day to find that he had duplicated it so I'd have a new one to wear for the next seven years! It probably sounds stupid to most people, but I love that he went out of his way just because he knew how much I loved that thing. Lasts much longer than flowers or chocolates, and he didn't need a special occasion to do it.