When my parents split up I wanted my family together again too, but it didn't happen. Parents don't split up without thinking about it very carefully.Try not to take sides and be friendly to both of them. Maybe they can get some marriage counselling?

Have u found out the biggest problem between them?Talk to each one of them sincerely , show them how much you care about your family ,let them know how important they mean to you !!!

give they time to think what is the best for their family, for their children... show how much u love them n ur family...show how much u care them... n dont afraid to tell what u think n u feel,let they know it...

Find out reasons. Find out common ground. Persuade(including hard manipulation) them and bring to family psychologist. If they don't want to be together,then I don't think that you can do much -they are adults.

Hello Angel Wei, You say they have been quarreling for quite a long time, thus the decision of separating is not sudden ,it built up gradually and this is the conclusion! Maybe living separately is better then being together and fighting all the time? I am sure you didn't enjoy their quarrels. Do you know of anything that could bring them together ? Certainly you know a lot about them and maybe you could give it a try,although I think they are grown up enough and it is difficult to make them change their minds. I wish you the best anyways :)