Christian Advice.....

Something has been bothering me as of recent. Due to the many conversations I have had with various friends regarding marriage, I've had a lot of things to think about and now I realize my confusion/complications comes in when I do not know what advice to give them. I guess my main problem is with divorce. I know some people say that "there is no grounds for divorce except for under biblical standards". Such standards are then classified as adultery. And that is it. There is no other reason that is "biblical ". At one point in my life (it could've been my wedding…) I heard that a man is supposed to love his wife the way Christ loves the church; marriage is supposed to reflect Christ's love for the church. I have heard the comments about being "unequally yoked", and I also know the verse about the unbeliever being married to the believer, and if the unbeliever doesn't want to leave and wants to stay married then they should stay married and they will be blessed (I guess I always viewed that as “if they respected and loved each other, there’s no reason they should be encouraged to separate.” My opinion…). But here's my problem: what if two professed believers get married, and then one or both change, and start to live a life or exhibit behaviors that are no longer in any way shape or form in alignment with Christ? What if that marriage goes from being an example of Christ love for the church to an example of "Sodom & Gomorrah"? What if the party that has walked away from Christ is choosing not to repent of their sins, they don't see any problem with the way they are living, and in turn start to ridicule the other for their continue walk with Christ? What if there are children involved in this? At what point is it then the Christian obligation? Duty? Right? To say enough is enough, this sin cannot be abided, and walk away? … Can the Christian rightfully walk away? How is it possible to despise the sin of disrespect of fellow man, and yet when a marriage partner: - makes lewd and disrespectful comments or gestures to the partner then laughs and say that's just the way men/women are - refuses to acknowledge they are hurting their partner - mocks them in front of the children - acts out (or demands to act out) fantasies that the other party finds repulsive under the blanket of “everything is acceptable in the marriage bed“ or “because you married me, even though you are uncomfortable you “need“ to do this/that because you are my spouse and it will make me happy” - Uses the marriage commitment as a weapon (“you’re never going to get rid of me”, “I will destroy you (reputation or financially, etc) if you try to leave”) encourage the offended partner to stay with them? Have we inadvertently created a double standard in our own Christian lives where sin is not acceptable or tolerable, except if it's with the spouse; then covered it with “marriage is private” so we don’t have to mess with the marriages that are a mess, and have to hold our fellow brothers and sisters accountable? I know I am in no place to judge others; we do not know the heart of man only God does. But when "man" (speaking of men and women) chooses (by their words and then actions) to walk away from the Lord, and they do not wish to reflect on their behavior and repent of it (because “they see nothing wrong with it, they just need to be accepted as they are…and you married them so now you just have to live with it“), what advice can I give them as a Christian? I feel that “pray about it” has become a cop out; for some people I’ve talked to, a natural death (for their partner) seems too far away, and suicide is not an option for them because they don’t want to leave their children to be raised by the offending partner. I guess I feel the cloak of “the irrevocable decision” has been placed upon marriage . Once you get married you are blessed or doomed for life; the fact that we are all sinners and we make mistakes is no longer applicable because marriage is "the end". *Note: I do not believe in “irreconcilable differences” as a reason for divorce. Also, I don’t believe “hurt feelings” are a reason to give up either. I guess I speak of a degrading of the partner as a human; they have become “objects”, or “possessions acquired due to matrimony”.