i agree most of your points, but not necessarily agree the last paragraph...
In the last paragragh, you concluded "there must be something/someone to damage the relation". No, i don't think so. It can be just they don't love/respect each other. (even worse, it could be that they hate each other).
謝謝你的來訪, 我為你又寫了下列文章, 請您來賜教批評: