boundaries - everything is about establishing and respecting boundaries with each other. professionally, it means respecting what each other brings and allowing them enough latitude to work the way they want. and you have to decide, constantly, where they are and when they can be broached. for example: is it ok to scream at each other when you're super stressed, when nothing's going right and when finances look bleak? is it ever ok? because you'll likely hit that stress point sometime after starting the business and it's going to mess with your personal life in pretty significant ways when it does. 

there are a thousand of these boundaries you'll have to negotiate. and, to be honest, you'll want to know something about how each of you handles adverse conditions (more than the good). 

i don't think 'wanting each other to succeed' is enough. i'd suggest you ask this question instead: would i create a business with this person if i didn't sleep with them each night? can we survive the ups/downs and walk away from the business without blaming each other if it fails? can we separate one realm from the other? if you can do a lot of soul searching and come to a 'yes', then you've got a foundation to build on.

in my situation, my wife and i figured out early on that we didn't want to go down this road together. we wanted a separate family life and work hard to keep that insulated from the inherent ups and downs of the external work. lot's of my colleagues make it work though. 

You may not remember the time you

let me go first.

Or the time you dropped back to

tell me it wasn't  that far to go.

Or the time you waited

at the crossroads

for me to catch up.

You may

not remember

any of those

but I do

and this is

what I have to say to you:

Today, no matter what it takes, we ride home together.

So sorry I don't know who wrote this cause the signature can not be read.  However, I have been in business with my wife for thirteen years. We come from very different back grounds. She is Brazilian and myself and old cowboy.   We have great days and not so great days, which usually involve money.  However true to the poem, which hangs in our bathroom over the toilet....we ride home together everyday, before we put our heads on the pillows at night and fall to sleep.   Best of luck to you.