It's what I call the "happiness syndrome". It has a proper name but I can't remember what it is.
People are more attractive when they are happy. It's the way it always works.
I always tell people that if they are looking for someone, then they won't find them. They need to stop searching for Mr/Ms Right and be content with their life and they will come to you.
Sadly, it also works when you don't want it too, like you've found out.
Also, the devil you know is always more secure than the devil you don't know. No matter how bad it was between the 2 of you, it's more secure than the unknown.