I, for all outward appearances, had the appearance of a pure holiness woman. I told my husband things about me after his proposal and before we married that even my roommates of several years and close friends did not know.
It turns out that 21 years into my marriage, my sister got viscously angry at me and I had to leave her home in order to keep from having a deep and sustained fight. After I left, she decided to give my brother and my husband an earful about my past in the deliberate attempt to deliver a mortal wound to me and my marriage. Only that did not work out for she underestimated the solidness of our marriage based on love for each other and for God and truth. She assumed that I kept certain things back from him.
My husband came home, seeing the attack for what it really was and commented on her motive for saying all of what she did about me. Some of what she said was correct, some was incorrect...pure embellishment on her part to make me look worse in the situation that I made for myself so many years before my husband and I met.
There are many first marriages that wrecked because the couple was not mature enough to marry in the first place. The love bug (is it really love or sexual desire?) bit them and for the first few years they love each other until reality sets in.
A sexual mistake at the age of 16 is pretty obvious that he/she was immature at the time it happened. It is an act that he/she should have to face the reality that it cannot be undone. If the engagement is destroyed, then the partner cannot deal with her immature act. He is expecting something that isn't and it is better if he knows it before marriage because there is always someone who knows and would be willing to divulge that information when it is convenient for them. Reputations change with a person's actions. Paul's reputation was of persecution to believers...until he repented and became a believer himself. Any mature adult who believes themselves to be Christian would consider her works since she repented of her sin.
As for the woman who told all to her future husband and he threw all of that into her face with every fight....
this is on him. He cannot say that she deceived him beforehand. He is the one with a big problem and eventually this marriage will wreck ...not because of deception, but because he married her for the wrong reasons and cannot truly accept her as she is now. She hasn't broken his trust. He went into the marriage with his eyes wide open and now he brings back some past fault to rub her face in and that is not a loving husband.
Why bother laying it all out there? Because the old adage that "knowledge is power" is valid. Knowing what you are getting into helps you make informed decisions...that the other spouse does not feel cheated if he or she finds out something .
You lay it all out there and let the chips fall where they may. If the love doesn't last through the engagement with what they learn about each other, would it survive the shock after marriage?

Yep. That is one reason why our previous marriages did not work.
My first hid the fact that I was # 3 and that he had been in prison twice before we married. Yep. He told me it was none of my business.
It surely was my business and would have made a big difference if I had known why I was #3 and what happened that landed him in prison...not once, but twice. That one was on me for not waiting long enough during engagement to get to know him better. At some point in time it would have come out before marriage ...just as it came out during our marriage. I would not have felt so deceived and then burned when he spit out it was none of my business.
Ok I confessed all of that so that maybe people might see why it is so important to be honest with future spouses.