If I love you, or am your close friend, or am altruistic toward you, I might directly count your interest to some extent as my own. In economists' jargon, I might partially include your utility in mine. Hence you can trust me to some extent just because the effect of our interaction on your welfare will matter to me. We commonly trust our parents, siblings, close friends, spouses, and others who are close to us in this way within varying limits. One might wish to call these normative instances of trust. But the actual trusting is not different from the purely interested cases under the trust game or iterated exchange. If there is a normative quality to these instances from love and so forth, it is in the fact of the love or friendship and the caring for another that follows from these.

Russell Hardin, Trust and Trustworthiness, loc. 152