There are many ways to protect the finances of a couple in the thick of a marriage crises that don't involve a legal separation. There are alternate ways to establish child support and child custody other than legal separation. In fact, in most states a legal separation is the precursor to a divorce and implemented to create a framework for the final dissolution of the marriage.
Spouses that rally hard for a separation under the guise of needing it to feel safe and protected are usually up to something. Nobody needs to live apart and initiate the legal framework of a divorce (via separation) to "work on themselves".
