Most women have no interest in taking on a masculine role - especially not straight women. I don't see any reason why you should!
One of the things that makes relationships work is that the people in them aren't identical. They have different personalities, strengths, weaknesses, etcetera. And in straight relationships, they have different gender identity and expression. In butch/femme, boi/girl, daddy/boy, bear/twink and similarly structured gay relationships, the difference in gender expression still shows up. The overwhelming majority of humans on the planet are not in a relationship with someone whose gender expression is the same as their own. And that doesn't mean they don't value and appreciate their partner's gender expression - it just doesn't suit them.
Think about a body analogy. Are you attracted to male body parts on other people? Doesn't it make sense that you could be, even if you don't want them on yourself? I'm not straight, but even I know women can be nice to look at - I just don't want to be one.