On one hand, if soap is something that actually affects your economy, you might want to consider your spending habits. On the other, it's your money, your responsibility.
Choosing your girl's underwear is perfectly normal. Well, if she asks.
I think she has the absolute right idea. If lightly pushing doesn't work, push harder. And also that he is an expert at his own taste, which is what matters. Fashion trends are irrelevant.
A lot of stores don't allow trying on underwear and beachwear, unless you do it over clothes.
See? You're happy she chose something for you. That means she'll likely be equally happy if you choose something for her.
It's an apron, not a display towel. You get those dirty.