What does the woman know when she says 后来才知道 (hòulái cái zhīdào)? (Edit: It looks like I originally excluded some important content, so I expanded the snippet below.)

This question is about 后来才知道 in the following sentence, where a woman describes her developing relationship with a man:


  　　起初我是不同意的，可是他很会表现，不仅对我好，对我父母也极尽照顾，有一次为了帮我送父亲进医院，冒着大雨开车去省城，后来才知道，他为了帮我，把6岁大的儿子一个人锁在家里整整一夜，彻底感动了我，交往不到一年，我们结婚了。
  嫁给离婚带孩子的男人 我的生活只剩下两个字, guaixun.com


(The second part was part of my earlier question Did the man lock up his 6-year old son at home overnight? (把6岁大的儿子一个人锁在家里整整一夜).)

I translate this to something like:


  At first, I did not agree, but he performs well [i.e., impressed me], not only did he treat me well, he did his best to look after my parents, one time to help me admit my father to a hospital, he braved the rain and drove to the provincial capital, afterwards only then I knew, to help me, he took his 6-year old son and locked him in the house by himself for the whole night, which thoroughly touched me, and being in contact for less than a year, we married.


Perhaps this means that is when she knew she was in love with him.  Or maybe it means she only found out the man about helping her father after he was in hospital.  I'm not sure.

Question: What does the woman know when she says 后来才知道?
what the woman know afterwards is he locked his six-year-old son in the house for a whole night, just for taking her father to the hospital. Beacuase it is dangerous that locked a child in the house about a whole night, so the woman was  thoroughly touched.