Much to my shock, and I certainly never intended this, the 401(k)'s that STBX acquired before he even met me are going to be split with me via the QDRO.
He could have avoided that by simply being reasonable about what was acquired while we were married. But since he fought & won to keep for himself what was acquired during the marriage (think a couple hundred thou), his before-marriage assets are on the chopping block.
I never would have wanted to touch what he acquired before he even met me.
When it comes to Social Security, I'm entitled to whatever is the normal spousal benefits when he retires (assuming I don't remarry, which trust me, I won't be getting remarried). There's no calc for what he put in only during our marriage.
I'm not so sure your STBX can never claim his benefits. IIRC, he will HAVE to take distribution at some point.