I will have lived with my spouse in 2017, though, so my MAGI for Roth purposes has to be at the MFS level, not the Single level (though wouldn't it be great if I had left off a zero?).
We will be MFS because we're getting married at the end of 2017, so "married," but still tax dependents for that year, and if you make over a certain amount (~$18k, I think), you can't file MFJ if someone else is claiming you on their tax return. We debated trying to keep our income under ~$18k, but we both got very good, well-paying summer internships.