User blog comment:IamJakuhoRaikoben/Chapter 497: The Winter Mage, Review./@comment-73.191.17.103-20160818134854/@comment-7418318-20160818165916

Jose ordered specifically ordered Gajeel to destroy the Guild Hall for the sake or provoking FT into attacking them. Gajeel didn't attack Shadow Gear for fun though, but because he thought that attacking an empty building would be insufficient and he's proofen absolutely right by Makarov's refusal to retaliate prior to finding Shadow Gear strung up.

Either way Gajeel's attack on Levy came BEFORE their relationship started. They never even met before. Once they knew each other and weren't enemies any longer there was no abuse between them, unless you count verbal teasing, head-patting and picking her up by the scruff of her neck that one time in an attempt to motivate her into giving it her all.