Biblically speaking, the scripture addresses this quite frankly. The lone scriptural reason for divorce is adultery. But, it goes a step beyond. In that situation it also states that if a non-believer is married to a believer, the believer should not divorce the non-beleiver if they choose to remain married, but if the non-believer chooses to leave, the believer is not bound to remain married. The scriptures also adresses remarriage. If, in the case of adultery, the innocent party is free to remarry, but only in the Lord. Meaning, the second time around, the innocent party should re-marry a believer in the faith. A situation that is recommended, but not admonished for a first marriage, as it teaches that a person must consider to remain married to a non-believer because you do not know if that influence would cause them to become a believer. The Bible also teaches that the adulterer, if remarried would live in sin, as would the person marrying them. Now, would I fault someone for divorcing an abusive partner, or someone that has gone to prison for malicous crimes. No. But, the remarrige portion according to scripture would need to be closely studied by that person. A much more delicate situation. To play devils advocate, the bible also states not to defile the bed less you cause your spouse to be tempted. So, if one cheats on the other because of a refusal to have sexual relationship, then who technically has broken the laws. Either one? Both? Alot of this can be found in the Gospels, especially Matthew, and in the 7th chapter of 1st Cor. incase I mis-paraphrased.