I've worked in a similar arrangement as the tech founder for a Social Media Marketing Agency. My partner was design and sales focused, with a tremendously string project management background.
I can say without hesitation that the complimentary skillset was key in both landing our projects (both early on and as the company carved out its niche), the variety of perspectives were key in addressing any and all client concerns. Likewise from an operations standpoint it was very clear where the work fell, tech (dev, management, support) on my end, sales & design on his.
I was lucky enough to have a good friend as a business partner and to this day had no issues (eg. friendship troubles due to business). I'm no longer with the agency, but that was totally amicable, it just wasn't for me.
I'm not sure about services for "startup" dating like you've described. But I can suggest you look within your network for the complimentary skillset you think could handle the workload you'd like to shed, box in a few limited scope projects that you could pass on to friends/colleagues, and be realistic about how well those mini-projects go.
My partner subcontracted a few projects this way to me (he made some initial sales before incorporating), and after 2-3 very successful projects, we signed and got started for real.