A legal separation does not mean you are no longer married, it means simply that you and your spouse are no longer living together and need to abide by the provisions of your legal separation agreement.
Alimony is financial support paid by one spouse to the other as part of a separation agreement or divorce judgment.
If the couple lives in a state that allows legal separation, the right choice may be for the two of them to work out a separation agreement.
Since the terms of the separation agreement may become the same ones for the divorce judgment, each person should seek independent legal advice before signing.
If you aren't ready to divorce yet but you want to get certain issues settled between you and your spouse, you may want to find a kit offering a separation agreement form.