If we only saw the faith God built in Abraham through His relationship with him, that'd be a great story. But there's more: Abraham's servant, sent on a mission he may find dubious, also turns to God to make the seemingly impossible possible:
And he said, “O Lord, God of my master Abraham, please grant me success today and show steadfast love to my master Abraham. Behold, I am standing by the spring of water, and the daughters of the men of the city are coming out to draw water. Let the young woman to whom I shall say, ‘Please let down your jar that I may drink,’ and who shall say, ‘Drink, and I will water your camels’—let her be the one whom you have appointed for your servant Isaac. By this I shall know that you have shown steadfast love to my master.”The marching orders he'd received included the "what" of God's promise and the "who" of the God that made the promise, but when it came to the "how" of the mission, he also turned to God. His knowledge of and trust in God wasn't just through his master Abraham; he called on Him himself. And he didn't pursue the mission resting only in his own wisdom and resources; he asked God to make it happen.
And the story continues: Rebekah shows the hospitality and grace the servant prayed would reveal her identity. Though God is fully sovereign, His people aren't reduced to automatons. Each relates to Him, showing their own personalities and characters in the unfolding story.
The servant knows to watch for God's answer, and responds when it is given. By watching, he witnesses God's faithfulness, and by being witnesses, he and Rebekah can share the story of God's faithfulness with her family. When God's people see Him work, we are often called to share it with others.
Abraham's servant doesn't presume that what he's witnessed will dictate the response of Rebekah's family, however. God's action doesn't override the dignity He's given them to choose, and their freedom to do so doesn't diminish His power or His faithfulness in the least. There's always risk in being a witness—you can give an account of what you've seen, but who knows how others might respond?
Rebekah's family chooses to acknowledge God's work and His will, which they celebrate. And yet—perhaps surprisingly in a story, but not unusually in our experience—when it comes down to letting go, there's still an attempt to negotiate the terms. It's dealt with quickly and quietly enough, especially relative to Old Testament disputes, and the resolution (perhaps surprisingly in an ancient cultural context) hinges on Rebekah's decision to go and become Isaac's bride. As may have been the case for Rebekah's family, sometimes our reservations in following God may be rooted in good intentions and love for others, and we can only let them go and follow Him when we trust that His intentions are better and His love is deeper than ours.
The story closes with Isaac and Rebekah meeting, hearing (again, in Rebekah's case) God's faithful action, and trusting His intention for them in giving themselves to one another. Clearly, this is culturally a very different model of marriage than ours (I tend to snicker when I hear the phrase "Biblical marriage," because people usually mean some cobbled-together, culturally current version, rather than the craziness we see in actual marriages in the Bible), but perhaps there's still something to learn about how to trust God's faithfulness in marriage through this story. They didn't "court," and their "romance" probably wouldn't sell well as a movie, but their marriage was first and foremost about being caught up in God's story and His faithfulness to His promise. That's a pretty solid foundation.