A legal separation doesn’t end the marriage. Signing a separation agreement won’t enable the parties to re-marry.
Since the couple is still married in a legal separation, they don’t have to remarry if they change their mind about the separation and get back together. If a divorced couple changes their mind, they must remarry if they wish to recover their married status.
Note: The information in this blog is not legal advice. Consult a lawyer for advice for your situation.