Compare what each person can afford after essential commitments, then agree which costs are shared. An equal payment and an equally manageable payment can be different things. Choose an arrangement together and give it a review date.
Put the same numbers on the table
Write down take-home income, agreed shared costs and essential individual commitments. Separate necessities from lifestyle upgrades. An expensive home or holiday chosen by one person should not silently become the other person's obligation.
Compare three arrangements
An equal split is easy to calculate. An income-based split changes each contribution with earnings. A shared pot with agreed personal money pools more decisions. None is automatically fair for every household: consider unpaid care, income uncertainty and access to money as well as the arithmetic.
Check the money left afterwards
For an illustration, two incomes of $2,000 and $3,000 contribute 40% and 60% of their combined income. Applying those shares to $1,500 of agreed bills gives $600 and $900. That is an example to discuss, not a rule or advice about debt, tax, ownership or legal liability.
Start the conversation
Try: 'I want us both to enjoy what we choose. Can we compare what this leaves each of us with and agree a limit before booking?' Discuss a cheaper option, a different split and delaying the expense. Record what you agree and revisit it after a change in income or responsibilities.
Sources and further reading
These are general conversation aids. Related scenarios illustrate different perspectives; they do not establish facts about your circumstances.