I dare say part of the reason Flybe havent looked at doing direct European routes is because they dont have the right aircraft for it right now. The 195s are big and used on the heavy domestic, and mainland-to-Europe routes, and as for the dash, well would you want to spend 2 or 3 hours chugging along to Frankfurt in one? Hopefully that will change with the introduction of the 175s soon. Belfast isnt really at the top of the list for one, but rumours (yes more damn rumours!) within Flybe are that they are looking carefully at the German market (some destinations in particular), something very lucrative to Belfast...
Also international flights are a bit of an ongoing issue at BHD as nothing has been purpose built for Customs and Immigration, one presumes/hopes by not starting the new WW routes for a while BHD management will get off their backsides and do something, maybe build a few extra needed stands while they're at it.