[manc_lad]

I agree with this. If she's adding value and her input is worth her place on the cap table then it should be easy to resolve.

You do need to think carefully about what a breakup would look like. Relationships can go sour and if that happened what would the arrangement be if they couldn't work together.

Also, who makes the decisions? Does her allocation give them both a majority of voting rights?

It's not a typical arrangement, that doesn't mean it can't work but your co-founder has added complexity into the process.