Well, I'm a FL attorney who recently went through something like this. What follows is NOT legal advice, per se, but is just my general observations.
You can look up the FL statues on line and see what they say. http://www.flsenate.gov/Statutes/
Basically, if the title is in her name and not encumbered by the claim of another party (like a bank financing the bike, or an "AND" owner) she can sign the title over to you. You then take the title and a bill of sale to the DMV and title the bike in your name.
If she has no paper copy of the title, she can go with you to the tax office and get a speedy replacement title that day. She could then sign it over to you and you could then go to teh DMV and register the bike in your name.
If the title is in someone else's name, or there is an encumberance, you need a court order appointing the title to her, then she can sign it over to you. A divorce decree seems like a good reason for a court to order the title appointed to her.
Another option is to just ask the guy if he has the title, and if he'd be willing to sign it over to you. As long as she's selling you her rights to the bike (via bill of sale), that might be a viable way to resolve this if all parties are in agreement with what's going on.
You can probably do all this yourselves without hiring counsel. Most stuff on this level can (and probably should) be resolved without getting us lawyer folk involved. Just double check the paperwork.
That's all I gots ta say.
You can PM me on this if you want.