One of the things that I love about feminism in today's society is that it's all about, "Do what you want to do, but only for yourself," meaning that you should only do things if you want to do them. However, one of the things that irks me about feminism in today's society, is that this is often misconstrued as "do what you want to do, but ONLY FOR YOURSELF." See the difference?
What the original statement says is that if you want to do something, do it because it makes you feel good. The second statement says that you shouldn't do said thing for anybody but yourself.
(For the purposes of this article, we're going to assume that "the thing" is dressing a certain way for someone, as the title suggests. You can change that to whatever your "thing" is to tailor my point to your life as you see fit.)
I've read countless articles that describe how refusing to do dress up for your significant other gives you the opportunity to begin to base your self-worth off of what you want from yourself instead of what others think of you. The problem with this type of article is that it assumes that the reason you're dressing up is because your confidence stems from the reaction of this significant other to what you look like, or that you're only doing it because they want you to, not because you want to.
I've heard people tell their friends that they shouldn't do something because someone else wants them to. Heck, I've told my friends that they shouldn't do something because someone else wants them to. The difference with me is that I'm making sure that my friend wants to do it for that someone else, not because of that someone else. A lot of people have a hard time distinguishing the line between the two, no matter what side of the exchange you're on; and instead of boosting one's confidence, it can make them question their decision to the point in which they no longer want to do it.
I learned a long time ago to not do something if I don't want to, but I also learned that sometimes, even if I don't want to, it's going to make me feel better. If I'm having one of those days where I just want to throw my un-brushed hair into a ponytail and go to class in my pajamas, I try to make a little extra effort because I know it'll make me feel better and more confident. It's the same principle when I go on dates (whether they're dates with a significant other or first dates). The whole point is for them to like me for who I really am, right? So why should I feel the need to dress up for it?
For first dates, I do it so I feel more confident with myself, not (just) to impress them. With a significant other, it's because I want to impress them, and I love knowing that I do. And as I said earlier, this doesn't just apply to dressing up! This principle applies to just about anything — wearing makeup, dressing differently, trying something new, etc., etc. Whatever your thing is, know that it's okay.
Should you do something just to impress someone? No. Should you do something because you want to impress someone? Absolutely. As long as what you're doing makes you feel good, go for it. You've got this.