Trustworthiness

I'm in the process of reading the ELCA Human Sexuality: Gift and Trust document. I wrote a review of the original draft at the Journal of Lutheran Ethics last year. It was titled "Please Don't Omit." One disappointment is that they did omit some of what I encouraged be included, especially more substantial reflection singleness and monasticism.

However, right now my main question is:

Whence comes this focus on "trustworthiness." Although I understand trust and trustworthiness as a category, it is new to me as a guiding principle or theological concept. Anyone know why or where from?