The game lacks a Diplomatic aspect, some way of deterring attack without threat of the use of the military. I've played games that had- or tried to have- Diplomacy to be a part of the game and no one seems to have a handle on how to implement it successfully or creatively, so I'm not about to offer suggestions. All I am qualified to do is to observe that game mechanics do not offer Diplomacy.
Now, that said, I can think of a couple of things you can try:
1) Set up your production so as to minimize the amount of time between completion and collection. If you are sure you can log on every 15 minutes, build houses that produce every 15 minutes. If you can play once an hour, build once an hour production. And so on, until you reach the point of 24 hour production, logging on just once a day to collect (and I'm talking trade goods and supplies, obviously, moreso than housing and gold).
2) Try to "buy off" your tormentor by Aiding him on a very regular basis. Call it blackmail that doesn't cost you anything.
3) Try to befriend an even higher ranked player in your neighborhood and see if he won't "return the favor" against your tormentor. Let the bully see how he likes being bullied.
4) Put up the best defense you possibly can, with an eye towards making each Plunder attempt as costly as possible. Upper Age military units take alot of coin and supply to replace and a long time for the unit to heal up. Let him know he's been in a fight, even if he wins.