Over the years as my classes have struggled to come up with an analysis of ‘faith’, the consensus has been that faith is commitment (to a belief or person) that outstrips the available evidence/reason for believing that proposition, believing in that person. That is why some suppose love must be unconditional (not dependent on evidence/behavior). I see faith as contrasted to warranted assertability; if one has good evidence/reason for a proposition, then one is warranted in claiming it to be true (and this remains true even if, in fact, the proposition is false). To the extent that warrant is available, faith is not needed. That’s why Kierkegaard says, “I believe because it is absurd!” His point being that no evidence to the contrary could shake his belief; in fact, the more counter-evidence, the more faith is needed, just as the more evidence, the less faith is needed. Since an absurdity is a contradiction, it takes great faith, indeed, to believe it. For Kierkegaard, faith is literally counter-evidential.
And after the high-blown stuff, yes, trust (without evidence or sneaking or peaking) is necessary to good relationships (whether of the love sort or not).