I am not sure what to say on this, since all my relationships before getting married didn't last past a year.
My mother's cousin is in the separation process from her husband/partner (not sure if they were actually married or not) and both her and her ex jumped in new relationships as soon as they went official with their separation. Mind you that those guys have been together since they were in middle school and last year were proudly celebrating their 22nd anniversary together. It's like they just flipped a switch. Even their children have no idea what happened since they weren't arguing in front of them, although they are already grown and taking it well.
To me it's a bit serie honestly. Somehow it makes me think how in some ten years or twenty years my wife and I could wake up one morning and just call it quits. Meh.