Just a hunch

Could RJ's phobia be of the water?  Perhaps he never learned how to swim.  

There has been repeated water symbolism, boats, and MAR means The Sea, among other things.

Also, something makes me think of how Lorelei Martins wanted to go to the ocean -- because maybe it was a safe place where RJ wouldn't go.  RJ seems to spend his time in remote country places, farms, old and abandoned houses and barns, fields and parks.