Is there the equivalent of “pre-martial counseling” for a potential cofounder?

1. Get References: ask for references for previous employers/managers and coworkers. You'll want to focus those conversations around the potential co-founder's skills, work ethic, style, motivations and attitude.

2. Fear Setting: if you're not familiar, lookup "Tim Ferris Fear Setting." It's a good exercise to get all your fears and doubts and worst case scenarios down on paper so you can work through addressing them.

3. Operating Agreement: define and document a clear set of operating agreements outlining roles, expectations, separations procedures, etc. Hash it all out now so there's no confusion or guessing if things do fall apart.

4. Temp to Perm/Sweat Equity: if this person's truly motivated to be a cofounder with you, consider a short term trial period that's unpaid and non-equity with a clear set of tasks and goals. If they agree to it, and complete it successfully, they may have proven worthy to join.