Two people together in business? Without a formal arrangement, such as an LLC/LLP/Corporation, etc. With or without paperwork, that's a partnership. No NOW.
Key questions:
Purpose? Business
Nonprofit? Gee, we hope not!
Sole proprietorship? Owned by Party A and party B, so apparently not.
Are parties A & B married to one another? No*
Result: partnership or some other form of business arrangement: No NOW
* - in some states a married couple can have a sole proprietorship.
Listen to your Mom, Joey, She's got it right!