I think it's really a matter of who decides who decides to do it first. When you're dealing with a couple who does not have so-called gender rules, things are different. Then again, the reason for the strikeout is because women actually have been known to propose to men. It's becoming more common than you might think. Also, they drop not-so-subtle hints that they want to be proposed to. Sorry, just had to throw that in there.
Another consideration is who is more of the go-getter in the relationship. Some people are more apt to take initiative for a proposal than others regardless of gender. It's not to say that the two aren't equal, just that one may be more of a leader than the other. It's not something to worry about. When the time is right, someone will propose!