If you are planning a wedding, the ideas of individual wealth preservation and life after divorce may not exactly be on your radar. If they are, you might feel guilty about discussing a prenuptial agreement, also known in Ontario as a "marriage contract". (Unmarried couples can also enter into a "Cohabitation Agreement". Much of what we write here can apply in that situation as well.)
Domestic contracts have become increasingly common in recent years. Between cohabitation being more common and later marriages that involve significant separate property, more people are in a position to benefit from the protections of contracts, including a prenuptial agreement.
Gene C. Colman Note, 17 February 2020: You have found your way to this page on my blog presumably because you are interested in whether or not you can make a legally enforceable Separation Agreement with a mentally ill spouse. Below you can read one of my first blog posts dated 8 July 2012. I thought that it might be time to update that blog post's information.