Without a case you will generally not get a subpoena. You can sometimes do discovery in anticipation of a lawsuit, but only for information that would be relevant in the lawsuit. Florida is a no fault state. Whether your spouse is cheating on you is of course quite relevant to your decision about your marriage, but it is not legally relevant to any proof needed for a divorce, so the courts are not going to help you investigate whether or not your spouse is cheating. If you want to find that out and are unable to do so on your own, you will need to hire a private investigator.
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