This will not happen anymore if you use one of these joiners. The joiner should even help hold the seal in place for longer as it hold the seal against the door, instead of letting gravity and constant use pull the seal away from the door.
Ford Focus Door Seal Mk2 5 Door Drivers Offside Front 2005-2011 Ref 167
Ford Focus Door Seal Repair (pack of 4) 2011-2019
Ford Focus Door Seal Fix (pack of 2) 2011-2019
Ford Puma Door Seal Brackets - Seal Always Stays On - Parcel Shelf Bracket
Ford Fiesta Door Seal Mk6 3 Door Drivers Offside Front 2002-2008 Ref 171
Ford Fiesta Door Seal Mk7 5 Door Drivers Offside Front 2008-2017 Ref 83
