for me, it all depends on how it ends. My most important relationship ended on a good way, with both agreeing we should end it, and stayed friends. We loved each other, but we had to end it, so I just instantly knew I had to move on, I saw her as a friend and was over her in no time, it was happy, there was no pain caused by her.
My latest one, is hard. Im 80% over her, after 1.5 months. The whole thing hurt me, and after it ended and love stopped blinding me, I saw what my friends told me, that she used me and abused me, so I knew I had to move on. It's hard, I have no idea how I'm doing it, I guess it's the "I HAVE TO DO IT" treatment, I accepted we're not getting back together no matter how much I love her, no matter how I still think she's the one, I know I must let go, and forced myself to do it
I just keep telling myself that I need to get her out of my mind as she doesnt belong there anymore, and im focusing on other things like chatting with people, working out and music