This is a complicated matter - you are right to wonder about this issue.
There are several bases for analysis:
1. If you are married (or get married) to the co-defendant, you would have federally protected privacy rights to asociate with a spouse which the state parole/probation offices would have to acknowledge.
2. If not married, you have fewer rights. Conditions of parole and/or probation must be rationally and reasonably related to the nature of the criminal act. It is reasonable to tell a probationer to have no contact with a co-defendent (even if separately indicted).
So......step back and look at your situation based on this information. If you have a probation/parole officer, and if you have a good relationship with that person, consider raising this issue with him/.her
If the person we are talking about is also the parent of your child (though not married to you), it also could create a basis for the right to have contact and you should raise that as well.
Technically, under Florida law, simply associating with someone who has a criminal record is not a probation violation. It is when you associate with people who you know are engaging in criminal activity that it becomes a probation violation.
As for your situation, the easiest way to avoid the situation is to get court permission to see your fiance.