Three things with that: 1) Prenuptial agreements exist, you can alter the terms of the partnership. 2) As someone else mentioned, pre-marriage assets are gene

Three things with that: 1) Prenuptial agreements exist, you can alter the terms of the partnership. 2) As someone else mentioned, pre-marriage assets are generally kept separate. 3) Business partners enter into all kinds of arrangements - maybe one parter brings in less money but has more expertise, connections, or will work more hours over the life of the partnership.