Our personal experiences of coming out after many years of marriage and parenting are somewhat similar. But I knew I was bisexual when I married and explained that (or so I thought) to my wife before we married. Also I explained that I wanted an "open" marriage. She later told me that she was very innocent at the time and simply didn't know what I meant.
When twenty years later she left with another man, she told our friends that my "sexuality had changed". Funnily enough my 15yo daughter told me: "Oh dad, I've always known that you were probably gay!"