What we don't know is her state of Salvation when Jesus met her. Was she a believer, was she saved? Without that knowledge, then we only extrapolate the reason he didn't tell her to go back to husband x or y.
I relate to you because I too just went through the same kind of thing. My ex-wife and I are divorced, because there was a tremendous amount of pain and sorrow that I took emotionally, by someone that condemned me continually and accused me of doing things I've never done, and found fault with me for her unhappiness. And I'm sorry to say, but that description is just only scratching the surface of the problems we had.
I find it somewhat difficult that you didn't see a pattern prior to marrying this person. (Please note, not trying to condemn, but rather trying to see the root of what happened). Although one of the problems with courting is we seem to put on our "Sunday Best" when in fact we should be what we are to our prospective mate. But there should have been some indications.
Such indications were available to me, but I thought she had pulled herself above what her family typically did. I guess the nut doesn't fall from the tree in all cases. But she had a change in her demeaner in her mid 30's and by time she reached her mid 40's with the empty nest and the change of life happening, suddenly she started pulling apart
No, I wasn't the perfect husband, but there was never a scriptural reason for the divorce. She claimed she had total faith, yet in this matter choose happiness over faith.
I guess I have trouble then with why God and Christ would put forth all these various rules and guidelines that Christians need to follow, only to ultimately say once you've professed your belief, it no longer in the grand scheme of things matters.
Everything presented to the Christian is an ideal, but we all fail, and none of us lives up to the ideals. If you know someone that does every moment of every day, please send them my username, I want to talk with them