I always took life too seriously as a kid... but I also was born to very "serious" parents who were part of a very "serious" extended family. "Interesting" and "educational" was always on the agenda, but "fun" seldom was. Like you, I was socially awkward and made very few friends till my college years.
The story of your client leaving (and another appearing) reminds me of something one of my Teachers once said: "Whenever a door closes behind you, it also means you have just stepped into a brand new space, full of possibilities."
Yup, growing up was not easy for me socially. I had friends but I always felt like they just tolerated me.
It seems every time a door closes a new one opens within a short time. It really is confidence inspiring.