I think all Christians would agree that God's ideal for marriage is "one man and one woman, living together in marriage until parted by death."
We see this emphasized by our Lord in Matthew 19:3-12. As strict as the Pharisees were, they believed that divorce was permissible. The question they had for Jesus was, "Could one divorce for any and every reason?" This seems to be the same attitude we see in our own day. Jesus responded that the divorce should be governed by God's original intent for marriage, and not by the culture of the day. God made it clear that those whom He joined together in marriage, man should not separate.
Our Lord's questioners responded by asking why Moses commanded that one give his wife a bill or certificate of divorce. Jesus made it very clear that Moses never commanded divorce; he permitted it because of the hardness of men's hearts (Matthew 19:7-8). In a perfect world, there would be no divorce. In a sinful, fallen, world, divorce is a pragmatic way of dealing with broken relationships. While Jesus looked upon divorce as a "necessary evil" for those who live in a fallen world, it is never looked upon as good. Divorce, Jesus said, was never commanded, but only permitted. This was, Jesus again repeated, not the way it was in the beginning (divorce is one of the fruits of the fall).
Jesus was even more restrictive on divorce than the most conservative Jews. He said that unless it was due to sexual immorality, the one who divorced his wife and married another would be committing adultery. Virtually everyone was shocked to hear what Jesus was saying. Realizing that Jesus gave no "easy out" from marriage, the disciples concluded that it might be better not to marry. Rather than to try to persuade His disciples otherwise, Jesus said that staying single might be an option to take seriously. Some, He said, were born as eunuchs, while others were involuntarily made to be eunuchs. Some men even chose to become eunuchs for the sake of the kingdom. These were difficult words, but Jesus urged His disciples to consider them seriously.
This text makes sexual immorality the only basis for divorce. I disagree with those who attempt to take this text further than what Jesus has said. They tell us that Jesus meant for this to apply only during the betrothal period, before the marriage was consummated. They would turn to texts like Matthew 1:19, to prove their point. I would agree that the engagement was taken so seriously it had to be broken as though it were a marriage. I disagree that this limits our Lord's words to the engagement period, and not beyond.
What, then, do we say concerning Mark 10:11-12, which seems to teach that anyone who divorces and remarries is committing adultery? I would remind you that this is a parallel passage to Matthew 19. I understand that the reason why Jesus does not mention the exception in Mark's Gospel is that He is trying to emphasize "the rule" and not "the exception." That was the problem with the Pharisees. They had made the exception (there can be divorce, when there is sexual immorality) to be the rule (there can be divorce for any reason at all). Divorce was so rampant that Jesus wanted them to see that God was not permissive about divorce.
It seems to me that those who hold to this highly restrictive view fail to remember the purpose of divorce. Divorce was permitted because of man's sin; it was a protection for the innocent party. It gave them the freedom to re-marry, without the guilt of committing adultery. When I look at passages like Deuteronomy 24:1-4, it seems to me that divorce was granted so that the divorced party could remarry, without becoming guilty of adultery. Whether one can remarry, then, is determined by whether or not the divorce itself was biblical. A divorce on biblical grounds constitutes the right to remarry, in my opinion.
The only other biblical grounds for divorce that I find in the Bible pertain to a divorce that an unbeliever seeks because he (or she) does not wish to live with a Christian spouse. This is based on 1 Corinthians 7:10-16. I understand Paul to be instructing Christians nnot to divorce. If they have already divorced, the must either remain single, or they can only re-marry each other. The believer should not pursue a divorce from an unbeliever, but if the unbeliever wants out of the marriage, the believer should not contest this, and the believer would then be free to remarry.
The two grounds for remarriage, then, would be a divorce that involved sexual immorality, and a divorce initiated by an unbeliever.
There are a lot of fine points here, but these cannot be explored here. The only way that I see for you to do this is by seeking counsel from a trusted Christian who is a student of the Bible, and who can meet with both of you personally.
Let me make just a few other comments about divorce.
First, sin is always messy - it creates untold problems. Sometimes it is very difficult to sort out all the causes of divorce.
Second, I do not agree with those who say, in effect, "It takes two to sin . . ." This has various forms, but in the end it attaches blame to both parties in a divorce. Clearly none of us is "without sin," and so any of us (married or divorced) can be found guilty of sin against our mates. But I would also insist, on the basis of 1 Corinthians 7, that one may be divorced because of righteousness, and not because of sin. Jesus said that the world would hate us, just as it hated Him (John 15:18-19). Peter tells us not to be surprised if unbelievers turn against us when we are saved (1 Peter 4). Certainly, then, some marriages may break up because of the righteousness of one mate.
Third, I would say that there is a sense in which divorce is the "lesser of two evils." By this I mean that divorce is never really "good." It is not a part of God's original design for marriage. Those who are divorced biblically and remarry will have more challenges to face, more baggage from the past to deal with. The Old Testament does not allow the priests to marry a divorced woman, and not even a widow (Leviticus 21:7, 14). A priest can only marry a virgin (21:14).
I have married a number of people who have been divorced, but hopefully these have fallen into the categories I have described above. In each case, I have pointed the couples to the Biblical texts, and told them that they needed to study those passages very carefully. They need to be fully persuaded about the matter of divorce and remarriage. They need to be willing and able to live with their decision the rest of their lives, without going back and constantly second guessing themselves. They need to be able to endure the disapproval and even rejection of some, who will believe their marriage to be unbiblical. They must certainly be able to have on-going martial (sexual) relations without feeling that they are committing adultery. In this way, they must reach their own convictions on this matter of divorce and remarriage (Romans 14). You must be fully convinced in your own mind, and you must do nothing from doubt (Romans 14:5, 22-23).
In addition to being fully convinced that you can marry, you really need to be certain that you should marry. I was counseling a couple a few years ago who each had a divorce in their past. At the end of our study the man said something like this to me, "I've come to the conclusion that it is not just a matter of whether I can remarry or not. The most important question is, Will this marriage glorify God?" He was right (1 Corinthians 10:31).
I would give this word of caution. You really need to resolve this matter in your own hearts and minds, before you become emotionally attached and committed to each other. Most certainly, you must deal with this question before you become involved physically. In all too many cases I've seen people trying to deal with the divorce/remarriage questions after they have already gone too far in their relationship. You may need to give your relationship some distance so that you can think through the matter clearly. If you both cannot say, with conviction, that you can and should marry, then back away and give this up to the Lord. If God has marriage in His plans for you, He will surely have a mate that a marriage that will please Him.
One final word of caution. Be careful not to use my words, or those of another, to validate your actions. This is a decision you must make, before God. It is to Him that you must give an account, so think very carefully on these things.