I'm also working on a startup with my wife as cofounder. We haven't launched yet, but her skillset is a fantastic complement to mine. I'm a very strategic thinker, whereas she's a great tactician and good at organization. She's also brilliant (Ph.D. student in I/O psychology), which is one of the reasons I married her. :)

I think that most couples aren't capable of running a business together, but I also think we're particularly pragmatic and don't let emotions get in the way of our goals.

I also have found myself becoming MORE creative now that we've been married. That might just be because I didn't move out from my parents' house until a few months before the wedding, but I can say that the broad generalization of marriage destroying creativity doesn't apply to me.