Mardy Grothe, a psychologist with a long track record of counseling partners, answers the question almost every would-be cofounder avoids: What's really driving you to seek a partner?

"Many people, sadly, want a partner for the wrong reasons. I see a lot of people who want a partner because going into business alone is too scary. It's a maxim in psychology that ambiguity leads to anxiety, and there's nothing more ambiguous than starting up a new company. It's filled mainly with a lot of fear about what will happen. What will happen if I fail? What will happen if I succeed? People want to share some of the anxiety.

"A lot of other people become partners because they're friends. There's a quotation from John D. Rockefeller: 'A friendship founded on business is better than a business founded on friendship.' Just being friends is not enough on its own to justify a business venture. It's nice, but you also need to do a very candid analysis with your prospective partner: 'What are you bringing to the table, and what am I? Do we make a more complete circle together?' People make the same mistake as young lovers: they assume that friendship, like love, will get you through. It doesn't. It's what causes you to form the union in the first place, but it's not what gets you through.

"Those aren't necessarily bad reasons to become partners. But I think they're bad if you aren't aware that they're the primary reasons you're doing it. Blaise Pascal, the French philosopher, once said, 'The heart has reasons that reason knows not of.' When we're driven by factors that we're not conscious of, we're more likely to run into problems down the road."