Just for fun, let's turn the tables a little bit here. You find an SO. You become a couple (maybe marriage but in any case you are together 16 years). Then you lose your SO. While you are together you ask if she was ever married. She says "no" so you don't ask about children. Yet when she dies, you find out she was married twice before and had two children, that she kept hidden from you. So is this a forgivable thing? She omitted the children during the whole time. She didn't lie about the children (you never asked) but she did lie about that marriages. Forgivable?
See this is in the same vein. Information, which could be of importance, was withheld. Knowing it though would change the dynamics of the relationship certainly, but offering that info allows the OTHER partner the right to decide how they feel about it. When you decide for them, you are controlling and it becomes a matter of trust. You assume you now what is best for them. Can you see where the anger comes from? Can you see where the loss of trust comes from? And yet you still think you know best....put yourself in their shoes for a minute. You trust your spouse then you find out that that trust was ill placed and then you wonder WHY they won't work with you?