For women, it's candy, jewelry, flowers and sexy lingerie. Men stuff is heavy and practical. Women stuff is temporary and fragile. Candy gets eaten, jewelry gets stuck in a drawer, flowers wilt. Lingerie, if it does its job, is likewise not a long-wearing garment.
Chocolate is something women really like.
She eats the chocolate, blows the diet and kicks her self-esteem in the teeth, making her miserable. Not a very good Valentine's Day gift. The only safe way to give chocolate is if your mate has enough self-control to not eat it. That leaves it all for you, who has absolutely no shame about stuffing Roman Nougats down your neck by the handful. On the other hand, if you're going to buy her something you're going to end up consuming, you might as well buy her a tool box.