Oh without a doubt Toaster. Although from personal experience I've always found when a relationship is on its last legs I usually spend a lot of time thinking about weather its really over or how to end it. I think its just one of the steps you take in the process of breaking up.
Although thinking about it maybe its a sign that two people need to sit, talk and patch up whatever the problem is. Perhaps as much of a sign to mend the relationship as it is to end it? Relationships...you just HAVE to admire the hoops humans go through for love!