Somebody that I used to know.

“But you didn't have to cut me off
Make out like it never happened and that we were nothing
And I don't even need your love
But you treat me like a stranger and that feels so rough
No, you didn't have to stoop so low
Have your friends collect your records and then change your number
I guess that I don't need, that though
Now you're just somebody that I used to know”

I think when a relationship ends there is a process of "duel", a period of time according to each person. Then, slowly with help from friends and family, is exceeded. But I dont know if it's possible without those people.
When a relationship ends, something breaks. And when you make the same mistake often, nothing changes. Go back with the ex, its like pouring water into an empty shampoo bottle, or try to fix a broken mirror. In case of shampoo, you can put a little water, and it may work for a while, but its never the same. And in case the mirror, in the wise words of GaGa: "You can still see the cracks in the mxtherfxcking reflection"
But I guess people always loves hit the same stone ... Or its just me?