I would need to make some assumptions... let me know if any should be corrected.
you both file as single and neither has dependents.
you both use standard deduction
neither of you has any additional credits or deductions.
your finance's adjusted gross income $80,000 - $8000(401k contribution) = $72,000, and gross tax obligations ~$12,100
your's adjusted gross income $70,000, and gross tax obligations ~$11,600
Total tax obligations ~$23,700
If you file joint tax return - result will be the same.
However, if any of you itemize, claim student loan interest, deduction, educational expenses, have dependents, etc - result might be different... ... let me know if any should be corrected.