It wasn't until he left that I actually started meeting tons of other travelers. I've met many who are still friends many years on, albeit all around the world. I got to share experiences with new people and saw things through different eyes and cultures.
I think travelling on your own teaches a lot about yourself, and it drags you out of your comfort zone. No one wants to be that lonely guy behind a book at the hostel bar...
As for travelling in Thailand alone, I did that, and met some of the most fun people on my trip. The thing is, a place like Thailand is no longer a strange and distant place, it's full of travelers and backpackers doing the same thing you are. And there are few things cooler than traveler's karma, get a favor and then return one to someone else...
Doing things yourself isn't as lonely as it makes out to be...