Over time promises have lost their significance, their value. People make promises all the time and rarely keep them, either because of intentional manipulation/deception or they just forget what they promised. A promise just isn't seen as any more than an intention or goal, which is quickly overtaken by the current activities or focus. We change like shifting shadows.
No wonder we view the promises of God as hopeful ideas or good intentions rather than truth. We shouldn't be surprised when we have difficulty keeping our word that we expect the same out of God. We hope he keeps his word, but won't build our lives on that promise for fear it won't come to be and we'll have to find another way through.
Or maybe we expect that when we are intentional to thank God for his promises in advance, and our perspective and attitude changes that those around us will also change. That our circumstances or struggles will disappear into thin air or resolve themselves. Like trusting God is some magical potion, bringing God's promises to fruition as soon as we start to trust.
But this one thing I do know: God watches over his word to fulfill it. He doesn't forget or get distracted but is holding it, working it out according to his plan, teaching us to put it all on the line, to fully trust him and his ways. The time of waiting and trusting isn't for God's benefit, but ours. It's in those times our roots grow deeper, our faith is strengthened, and we realize just how faithful God is.