what causes separation?

Parting usually happens because of lack of trust to their partner both husband and wife couple and courtship.

And that often makes the couple split up is when being quarrels no one wants to budge no one wants to apologize then from that they split up.

It usually happens because the couple has not been married or recently dating, if it has been a long time maybe the trust of his partner will not be easy to lose and always there is a relent when there is a problem.
That young couple who still naively promised not to leave but all the same