Has Anyone Else Learned the Hard Way About Choosing the Wrong Co-Founder?

So… this happened about 2 years ago and I’m still recovering from it tbh.

I had this “brilliant” idea for a SaaS tool (yeah, I know, another one lol). But instead of going solo, I thought I needed a technical co-founder since I’m more on the business side. Found this guy through a mutual friend who seemed perfect — great coding skills, similar vision, and we clicked during our coffee meetings.

Big mistake. Here’s what went wrong:

First red flag I ignored: He wanted 50/50 equity split from day one, even though I had already done 6 months of market research and validation. But hey, I was desperate for a tech person.

Things started falling apart around month 4. He’d disappear for weeks without updates, then show up with code that barely worked. When I tried to discuss deadlines or priorities, he’d get defensive and say I “didn’t understand the technical complexities.”

The final straw? I discovered he was working on a competing product using OUR code base. When confronted, he claimed it was just a “side project” and that I was being paranoid.

Legal battle lasted 8 months. Cost me about $15k in lawyer fees and basically killed the startup momentum completely. The worst part? I had to rebuild everything from scratch because he owned half the IP.

What I learned (the hard way):

Vesting schedules aren’t just for employees — they’re CRUCIAL for founders too Clear written agreements from day one, even with friends Regular check-ins and milestone tracking aren’t micromanagement — they’re survival Trust your gut when someone’s communication style doesn’t match yours Now I’m working with a new co-founder (found through Y Combinator’s co-founder matching). We spent 3 months just working on small projects together before making it official. Way better approach.

Anyone else have horror stories about co-founder breakups? Or am I just unlucky?

Would love to hear how others vetted their co-founders or if there are red flags I should’ve caught earlier.