My tax professor used to declare (comically) that he and his wife were getting divorced every year back when I was in college for tax purposes.
Generally, there is a "marriage tax." It's because of the income tax brackets and effective tax rates. Sometimes, additional credits can be had, or if one person has income while the other doesn't etc., things work out, but with both of you making income, you're almost surely better off remaining unmarried for tax purposes.
Thank you for your question.