Why does everyone have to speculate so much?
Isn't it plausible enough that Georgie was ready to settle down and Dec wasn't, causing them to split? Maybe he felt she wasn't the right person? Better to split than have her walk down the aisle under false pretences.
I can't think of a better way to say what you have. All I will say is that I completely agree with you.
Georgie is at the age where she'll here a certian clock ticking and Dec is just not ready to settle down.
I hope they both meet new partners that will make them happy and complete.