I'm going to get blasted for this, but here goes anyway.

I'm willing to bet that the majority of founders are single males who do not understand what marriage is all about. I have not had the experience of being part of a start-up, but I do have 6 years of marriage under my belt. I cannot imagine any circumstance where being someone's co-fonder is in any way like being married to them.

Well, I've been married for five years and I'm a co-founder. I don't know if it's like this for everyone, but for us there are a lot of similarities. I think you can easily s/co-founder/wife/g on the list below.

- My co-founder very intimate knowledge about me. My credit score. My favorite things. My political positions.

- My co-founder knows me well enough to manipulate me, if he wanted to.

- My co-founder is really aware of what a rotten person I can be.

- I can talk absolutely candidly with my co-founder. About anything. Even medical stuff.

- My co-founder almost certainly knows exactly what I'm doing right now, even though he's 1000 miles away from me.

Same boat. It was interesting to invite a third person into our life like that. But this is a commonplace in many professions, no? Cops, soldiers, etc.

However, the wannabe founders reading it are also probably single males who don't understand marriage. We do, however, probably all share a very similar caricature of marriage - and thus the analogy is useful in communicating the bizarre mix of love, hate, co-dependence, shared depression and elation, occasional jealousy and careful maintenance that characterizes the relationship between two guys in a foxhole with laptops.

it's particularly interesting when your co-founder is female. (or, you're a female co-founder teaming up with a guy.)

That is interesting - have you done this? How did it go?

Yes. I'm the XX. It just seems a different dynamic than you'd get between two guys or two women. (Obviously I've not directly experienced the former, but I've seen it from the outside enough - it's kind of the model.)

I'm a kind of bloke-ish girl, but even so I think I worry about feelings and opinions and perceptions a bit more - I bring that aspect of looking at situations to the startup. 'Course, my "job" is to code, whereas my cofounder is meant to be thinking about other people; it gets interesting.

There's also an entirely different dynamic: minority programmes. I took part in Astia, a women-in-business networking and training group. All the contacts from that equate the startup with me (the woman) and my cofounder's not being treated very well by them at all. (There are a few other reasons beyond gender there but it is something I doubt two-guy startups have to face!)

Right! So most unmarried founders are not really thinking marriage, but girlfriend. Or rooommate.

I won't blast you, but I will disagree. Relationship problems seem to span across relationship classes, and tend to involve breakdowns in trust and communication.

It seems like trust and communication are fundamental to both romantic and cofounder relationships. Maybe you can't judge a founder after watching them try to drunkenly pick women up at a bar, but I'd be surprised if there wasn't a correlation between someone's ability to maintain successful relationships in both categories.

I compared it to marriage (and yes, I am married) because when you start a company with someone, you're beholden to their weaknesses as well as benefiting from their strengths.

For example, if your co-founder only has 3 months of living expenses saved up, well you've got a deadline to get more money.

Plus in the YC-model startup, you're usually living in very close proximity with your co-founders, so you need to get along with them as roommates as well as partners.

I will tell you one aspect where they're different: I can show a business partner some very evil and cut-throat side of me that I will do anything absolutely necessary to shield from my girlfriend.

Yeah, you're not married--you can't hide that stuff from a wife forever.

Just like modern marriage, startups aren't forever.

I suspect, however, that you refer to sucessful marriage, which could easily span several successful startups.