T.N.
I believe it can.
I googled "how to file for a Voluntary Affidavit of Paternity in Michigan" and this is what I found.
http://www.michigan.gov/documents/Parentage_10872_7.pdf
However, he will never know unless he tries. I think he should CALL his local county's family court with a specific question. At least, that's what I would do. As long as he understands it is a monumental lifetime financial and emotional commitment, not just cuz he's mad at his gf.