Why do i want what i cant have?

so i in this weird situation. Its quite dum and probably pretty immature. Its wierd tho i cant help it. Me and my girlfreind split up and weve been trying to work it out, but im not sure if its happening. anyways whenever she tells me she doesnt want it to work out, thats when i start to miss her and realize that i want her back. then later when she decides she wants to work it out i decide that i dont want her anymore. I cant figure out if i really want her back or not. i only do when she doesnt. I thnk its my ego or something.