Beliefs: If you are having a hard time finding evidences of grace, would it be possible that your functional belief system is that sin triumphs over grace? In other words, do you really believe in the life-changing power of the gospel or are you secretly resting on the “security” you find in human performance? (If you derive more comfort from someone’s track record, you are slipping into legalism.)
Trust: Do you really trust a man-made legal document like a prenuptial agreement more than God’s Word?
Direction: How have you progressed to this point in your relationship with your boyfriend? Have you been praying along the way? If so, what guidance have you received in prayer? What has been the counsel of others? Is marriage the logical conclusion of this direction?
Cravings: When you see “unhappy” marriages, what you are really seeing is unresolved conflict and competing idols at work. This is what we learn in James 4:1-2. “What causes quarrels and what causes fights among you? Is it not this, that your passions are at war within you? You desire and do not have, so you murder. You covet and cannot obtain, so you fight and quarrel.” With this in mind, how have you and your boyfriend progressed in examining your own motivations and learning to resolve conflict biblically and humbly? That may be much more important to your future happiness than the track record of other people’s marriages.
Purity: This has not been directly mentioned, but it’s important to bring up. If you are not following God’s plan for the good gift of sex inside marriage, then you may already be setting the stage for divorce. By trying to partake of what God has clearly said is off-limits for unmarried people, you are clearly on the path of committing the same self-centered sin of adultery after marriage. I’m trying to be clear here, but not harsh. It’s important not to sugar-coat this point because the tug of our flesh is so powerful. If you have been sinning sexually, I would appeal to you to repent. I would also recommend that you confess this sin to a mature married couple and/or your pastor and his wife and asking what steps you need to take next for restoration. It may be that you need to establish new boundaries or you need to step back from this relationship altogether for a period. I don’t know, but those who are in your local church who know you better would.
Additionally, I would suggest you both could benefit from reading some Bible-centered books on marriage to make sure you are clearly understanding God’s purposes for marriage. One that comes to mind immediately is "Love That Lasts: When Grace Meets Marriage" by Gary & Betsy Ricucci (Crossway). I think you will find many encouraging perspectives about marriage in this book.