Well, we can start with the original source, the Torah itself. In Parshat
Ki-Taizay in Dueteronomy, the Torah discusses the issue of getting divorced
and the result is that if the marriage isn't working and can't be saved then
it's actually a mitzvah to get divorced rather than punish each other for
many more years. There is more discussion among the commentators on the
subject but this is the basic idea according to the Torah.