Without the advantage of personal counsel I will do my best to give you as you call it "the bottom line on divorce."
First, God hates divorce but He has allowed for it out of the sinful hardness of man's heart.
Matthew 19: 7-9 says
"Why then," they asked, "did Moses command that a man give his wife a certificate of divorce and send her away?" Jesus replied, "Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. I tell you that anyone who divorces his wife, except for marital unfaithfulness, and marries another woman commits adultery."
It is never God's perfect will for one to divorce. But the sin nature being what it is God has made very carefully defined provisions for obtaining a Scriptural divorce. Divorce is not the unforgivable sin. For that reason, we need the many good resources on how to put our lives back together again after such shattered dreams brought on by divorce.
Second, it is never God's will for two believers to divorce under any circumstances. There are no Scriptural provisions for 2 believers to divorce -- ever. The reason for this is that whenever a true Christian sins or fails in his or her marriage that person will, out of love for Christ, repent of their sin and seek reconciliation. Husband and wife must love each other in their love for Christ. Refusal to do so merely proves the love of Christ is not in them and their salvation needs to be questioned.
Third, when two people claim to be Christians and they pursue a divorce in violation of the Word, they must come under the discipline of the church to ascertain the validity of their faith. If, in conjunction with the leaders of the church, it is determined that one or the other party is insistent on pursuing a divorce and refuses to repent, then the church has the authority to declare that the hardened one is not a believer. This can never be done in isolation but must always be done in conjunction with the elders of the church. And they must be committed to enforcing the divorce parameters spelled out in Scripture:
Matthew 18:15-18 says
"If your brother sins against you, go and show him his fault, just between the two of you. If he listens to you, you have won your brother over. But if he will not listen, take one or two others along, so that 'every matter may be established by the testimony of two or three witnesses.' If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, treat him as you would a pagan or a tax collector. "I tell you the truth, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven."
If a church is not willing to practice church discipline for the purpose of bringing repentance and restoration, then one should question whether or not they should remain in such a church.
Fourth, if one party is a believer and the other is not, then divorce is allowable under only two conditions. The "desertion clause" of 1 Corinthians 7:10-17 says,
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I was married to a pastor for 20 years; this was a 2nd marriage for both.
He was having an affair and then entered a committed relationship with a woman while still married to me. He made no secret of being involved with this woman. He left and also left Church. He has never acknowledged his sin or repented of his persisting adultery. He has recently been called to a very prominent church in the city. He, of course lied about the reasons for the divorce. He publicly humiliated me and his children. I acknowledged to God that I am battling bitterness - why would God continue to bless a man who is unrepentant about his adultery and sinfulness. Churches will never change if they allow leaders to carry on this kind of behavior.