debt-to-income calculation when only one spouse is investing?

[Sara Walters]

Hello BiggerPockets! I'm new to investing and hoping someone can give insight on a financing question I can't seem to find the answer to.

My husband and I own a single family home in Boston, MA, and are both on the mortgage for the house (but were unmarried at the time of purchase last year), which is a conventional 30YF. I have been in conversation with a potential investment partner in Texas, a friend of mine who is single and does not hold a mortgage himself currently, about the two of us teaming up to buy a property there (either a single family home or a duplex most likely) to BRRRR. One scenario would be buying and rehabbing the property with cash, and then doing a cash-out refinance to recoup the capital, versus buying the house with financing and then doing a subsequent refi. In either scenario, my friend and I would either be applying for a loan together, or I would apply for it under my name only. My husband approves of this venture, but has no interest in being involved himself and would not want his name on any of the paperwork.

My question is: would a lender use the full amount of my current mortgage in calculating my debt-to-income ratio, or would they say that I am only responsible for half of it, since my husband's income also goes towards that loan? I am confused about how to get approved for a new loan by myself or with a business partner when my current debts and assets are shared by a spouse who will not be a part of the deal.

I can give more details if necessary but hopefully the basic question makes sense. Thanks in advance!

Sara