When my relationship was on the edge to end, I used to think that if I really try hard and continue to make efforts, which I actually did, I can save it. I can make the person stay. I really tried my best - I apologized for my mistakes, I did constant checks, and tried to consolidate things, but at the end I found them going. It all ended up. I had my breakup which was so hurting, and after that it has been 2 months and 7 days processing it, and I have been to a lot of conclusions. Every time I observe things, I come up with new realizations, and with time, the dilemma of the breakup has been more and more clearer to me. And now I realize all that time when I was making efforts, that was all not worth it, because the other person was just trying to detach themselves from you - maybe consciously or unconsciously. At the time, she had already lost interest in me, and I realize I was in illusion.
Now I have learned to let people go - let them explore the world, let them meet new people, let them realize what is best for them, where they belong too, and where they really find happiness at the end. If they were meant for you, at the end, if they realize they are happy with you, that they are really meant for a relationship with you, they will come back. And if it will be meant for you, you will return back too. But I know it's not an always and usual case. Mostly things don't work this way. People go and go on, and you move on too, because it's very rare that once the universe separates you from someone, it's for a reunion with more self awareness. Most of the times, the universe diverts you to other things and other places, purposes where you belong to. So be hopeful, keep working on yourself, and cheer for the person's happiness you loved and also for yours.