我想知道此处的which 从句的成分分析？

One tragedy in many marriages is that the romantic love on which it was based never ripened into friendship. 很多婚姻共有的一个悲哀是，本来作为婚姻起点的男欢女爱却从未成熟到互敬互爱的境界。

主语：{(One 数量限定词作定语) (tragedy 主语) [ in (many数量限定词作定语) (marriages 介词宾语) 介词短语作后置定语 ] }；谓语：is 系动词作形式谓语， 

表语从句：that the romantic love on which it was based never ripened into friendship.  

其中(the romantic 前置定语)(love 表语从句主语 )[on (which it was based 介词宾语从句)介词短语作后置定语](never 时间状语)(ripened into 动词短语作表语从句谓语)( friendship. 表语从句宾语)，由于ripen不及物，也可以把 into friendship看成状语，而friendship是介词宾语

句子分解可得：
The romantic love never ripened into friendship
The marriage is based on romantic love.
此处的it指代marriage

on which it was based,是个定语从句，介词on+which结构，修饰前面的先行词love.be base on意思是在……的基础上。

（One tragedy）in many marriages （is） that the romantic love on which it was based （never ripened into friendship），base on which,即是base on love. 定从。