agressive pig

Question
I have a pot bellied female pig and she is NOT so nice to everyone and everything besides me.  but she has gotten a lot better since being fixed.  problem is, when she was 1 1/2 i got a male.  he has always been incredibly sweet to everyone. complete opposite of her.    they have been very close for the past 2 1/2 years.  the female would occasionally nip at him.  but no big deal.  out of no where, two weeks ago, the male starting attacking the female.  he hurt her pretty bad. I separated them for a week to let her heal.  All week i keep letting them back together and he keeps going after her.  why would this happen after 2 1/2 years of them being close?  she is almost 5 and he is almost 3.  He was also fixed when he was a baby.  I can't keep them seperate for much longer.  Is this something that could pass? Should i intervene when he goes after her or let them fight it out?  she had many gashes from him last time, some just missing her eye, so I'm worried about her.  she kind of runs away when he's coming after her, sometimes she fights back.  She was always the dominant one and he was the submissive one, but she doesn't seem like she is willing to switch rolls.  please help!

Answer
Pigs reach emotional maturity and adulthood at age 2-1/2 to 3. So this could be simply a matter of the male pig trying to be the top hog. The goal in pig confrontation is to really scare the other pig, not seriously injure them. But, that's a fine line that the pigs can unintentionally cross.

If the female was sick or not feeling well, that could have triggered the males aggression. So do make sure the girl is ok, acting ok, eating ok, etc. If anything seems "off", she should see a veterinarian.

Assuming the female is Ok and this was just a particularly bad pig dispute. they can be put back together. If possible, pick a fairly neutral place, like an outdoor pen. Scatter pellets or popped corn around on the ground, put vasoline on their ears and tails so they can't latch on, and leave them be.

If the males tusks are particularly sharp, you might want to try blunting them with a nail file or emery board for everyone's safety