是要英文解释还是中文翻译呢?我都给你好了.
That means if kept seperated for a long time,married couples are likely to suffer unexpected problems,including being alinated and strange to each other,which may eventually force them to split up.
中文翻译：长期异地分居可能会导致夫妻不和.
至于为什么用long distance,应该结合上下文去理解,可能文章中是为了强调相隔很远,并且long distance有持久性的意思,和long time有所呼应.