AITA for refusing to live with my girlfriend if she insists on splitting expenses by income instead of 50/50?

When my grad-student girlfriend suggested moving in together, I thought it’d be exciting—until she said we should split bills by income. That’s when I realized our money values might be too different to share a home.

I’m 28 and earn a good living running a small contracting company. My girlfriend, meanwhile, is in grad school living off a modest stipend and loans. Her rent nearly eats up her income, and she’s been struggling with bills and debt. When her landlord announced a rent hike, she suggested moving in with me—it made sense financially and logistically since I live in a house owned by my grandparents and don’t pay rent. I currently have a roommate who covers utilities as “rent,” and my girlfriend said she’d want him to move out if she moved in.

I told her we’d split expenses 50/50, but she insisted it should be proportional to our incomes—which would mean I’d be paying almost everything. When I said that wouldn’t work for me, she called me selfish.

From her perspective, it made sense—she earns much less. But I explained that even a 50/50 split would drastically improve her finances since her current rent eats her income. She’d pay less overall, and I’d actually start paying more than I do now, since I currently cover no utilities. But she still argued proportional was “fair.”

"If you insist on splitting expenses by income, then we can’t live together."

She was furious, saying I was stressing her out unnecessarily. But money has always been our biggest fight. Every year she takes a summer trip on her credit card and just bought a new car with a $700 monthly payment—something her mom helps her cover. She’s told me repeatedly that her money is her business, but still wants our shared costs tied to what I make.

"I’m fine with proportional if we’re pooling everything—but not if I’m footing more while having no say in how she spends."

For me, this isn’t about the money itself but the principle of shared responsibility. I’m saving every penny to grow my small business. If we lived together, I’d expect teamwork, not independence when convenient. So, I told her the move-in plan was off unless we agreed on equal footing. Now she’s angry, and I’m questioning whether we see partnership the same way at all.

🏠 The Aftermath

We didn’t move in together, and things have been tense. She still says I’m unsupportive, while I feel I dodged a bigger financial mess down the road.

My friend kept the room, bills stayed the same, and my savings plan continued. My girlfriend, meanwhile, is still searching for a cheaper place for her and her dog.

We still talk, but arguments about “fairness” in money haven’t stopped. She believes I should want to contribute more because I earn more. I think fairness means shared effort, not adjusted percentages.

Sometimes “fair” looks different depending on who’s paying the bills.

It’s not about greed or control—it’s about having the same expectations for partnership. Still, I know how it looks from the outside: rich guy refusing to help his struggling girlfriend. That’s part of what makes it sting.

💭 Emotional Reflection

Money exposes values fast. She equates proportional expenses with compassion; I equate 50/50 with equality. Neither view is inherently wrong, but they reveal very different ideas about partnership.

In relationships, “fair” often collides with “comfortable.” She’s used to managing alone, while I’m used to structure and saving. It’s hard to merge those worlds when trust over finances doesn’t exist yet.

Reasonable people can see both sides: she’s struggling and asking for help, while I’m protecting boundaries and future plans. The real issue isn’t math—it’s alignment.

Reddit readers had strong opinions about whether income-based splits are fair in this situation:

If she wants proportional, she needs to share finances fully. You’re not her sponsor; you’re her partner.

Fifty-fifty is fine when both partners benefit. She’d still save tons moving in with you, even at equal split.

Money fights early on often predict long-term incompatibility—this might be a red flag for both of you.

Most commenters sided with the 50/50 principle, arguing that proportional splits require shared budgets and transparency. Others empathized with her tight finances but warned that mixing mismatched money habits can breed resentment.

🌱 Final Thoughts

Fairness in relationships isn’t one-size-fits-all—it’s about what both people can agree feels equitable and sustainable. But when transparency or teamwork is missing, even the math becomes emotional.

Sometimes love isn’t enough to bridge a financial philosophy gap; the numbers only highlight the trust that’s not there yet.

What do you think?
Would you have left, or stayed and kept trying to make it work? Share your thoughts below 👇