New Couple Conundrum: Who Pays the Rent?

The journey of my relationship status went from newly single to Tinder to in a relationship.

Now, the real fun starts. My girlfriend is moving in.

We've got all her clothes in the closet, drawers assigned to his and hers, and we've even got matching toothbrushes. Question is, who's gonna pay for all this?

Normally, when you've got platonic roommates, the deal is you split the rent right down the middle, right? So what do you do when it's your romantic partner? Do I pay for the rent, while she pays for groceries/utilities? Do we split the rent, and I pay for groceries/utilities (since it's technically my house)? We've got separate bank accounts, so shouldn't this be easy?

For me, it all breaks down to math. I figure you take an average of all the bills we share: Rent, utilities, groceries. Add those up, and divide by how much income we're each bringing in. For example (and I'm making these numbers up):

If I make $50,000/yr, and she makes $40,000/yr, I'm bringing in 1.25x the money into the house that she is. $50,000 + $40,000 = $90,000. $50,000 is 55% of $90,000, meaning I would pay 55% of all the bills, and she would pay the remaining 45%.

Simple, right? Math is so romantic.