you have a point when there are long term accumulated assets. OTOH, is marriage really the right answer if you are not comfortable sharing everything? Personally I would find it difficult to be married to someone who I didn't absolutely trust.
At the moment, the substantial majority of my wife's and my assets are only in her name - due to an inheritance. We kept them that way in case I go into a nursing home before I can kill myself, to protect her. Yes, she could run off and leave me with very little. I just trust her not to do so.
OK from my POV the keeping pre marriage assets separate is not to do with trust. No I could not marry someone I don't trust.
It is about protecting myself and my children. It is different in a first marriage with shared children because both parents will hopefully have the kids best interests at heart in the event of a death.
It may be odd to some but my ex and I still own property together and have not changed the titles to Tenants in Common which would be the logical post divorce thing to do. This is because I trust that if I died first any money from the properties would help to fund my kids futures.
Now if he were to remarry and we still held property it would very quickly be changed to Tenants in Common.
I trust my partner implicitly but it sits well with both of us that our assets are separate. It just makes life easier, there is no argument pre or post death and no emotion attached to it.
But like I said earlier there is also something missing which is the feeling of building a financial future together, this we will achieve in a complete 50/50 contribution way and keep it separate from our pre marriage assets.
Life is too short and people work too hard to risk it all later in life. As most divorced people know, there is no guarantee of what the future holds. We once loved and trusted our partners but for whatever reason it went wrong and in divorce there are few people (sadly) that can do it amicably.