Young couple goes on van tour of US, boy comes back with van - no girl
It might of been the possibility, that Brian's dad's brother sells yachts, which according to that link that mentioned this awhile back, had offices in Mexico. Nothing really confirmed for sure though.
Anyways, according to this CNN video, the flight to Florida on August 17th, that was reported earlier, has been confirmed. The reason is that Brian needed to clean out the storage unit, so they could save money and have more time traveling.
Speculation time:
Hardly seems believable, because the flight would of costed the same amount of the savings would of been, especially since it was a flight that booked at the last minute. It might be more likely that after the fight and police incident, things turned worse, and Brian had to get away for a bit, and flying back to Florida seemed like a good move.
While away, maybe Gabby had a change of heart, and wanted Brian back. Maybe things were good for a day or two after Brian came back, then Gabby and Brian were back at it with the fighting, emotions running high, and maybe someone snapped?!?!
If Dog the Bounty Hunter was on Brian's track, maybe he took the wrong turn some where, because Brian hasn't been found yet.