User blog comment:IamJakuhoRaikoben/Chapter 474: In the Moment of Complete Silence, Review./@comment-73.173.42.152-20160224130450/@comment-7418318-20160224221709

But that's exactly it: Meredy tried to kill Gray, without success (and Gray might never have learned that she did). She only made him feel a little indirect pain from Juvia hurting her own leg.

Under Ultear's controll on the other hand, Jellal tortured and killed several people. He didn't just try and fail, but he did kill people, including Simon. Because of Ultear many lives have been destroyed. But even despite all everyone except for possibly Millianna, Kagura and Ultear herself have forgiven Ultear (or just don't care for what she did). So if they can forgive Ultear and Jellal for all that, why not forgive Meredy for the far less severe matter?