There are just some things best left unsaid. Cliché but so true. I'm over doing certain things because I'm now less naive and much less stupid. If I'm not in that place when I met him, why in the world would I bring it up? Whilst it may not end our relationship, it does give him licence to potentially judge me unfairly and that could well change his perception of me even if he really doesn't want that to happen. I'm not about being judged over previous mistakes that have nada to do with him in the first place. Nor do I feel just because I make someone my SO or DH that they have full access into my whole entire life history. My own mother isn't even privvy to that.
The things I've likely to not disclouse to an SO are not very serious but extremely personal and some are just plain silly. There's no need to re-hash it. If an SO/DH was to tell me absolitely everything, then fine. But I'm not bothered. Just tell me the serious things (like another poster said - children, sexual orientation, disease etc) because those are really the things worth stressing and divorcing/leaving over.