Well, i wasnt going to mention this as it still riles me a bit, but here we go.
Im playing HRE, and everything's rosy. I allied fast, expanded faster, and got myself a nice little gross-deutsches-reich before the pope could even sneeze at Frankfurt.
Well i notice my allies in Denmark are experiencing a little "viking invasion" with regards to insane norsemen with ridiculous beards going medieval on the danish realm. "Whatever" i thought, untill the Norse took Arhus and assaulted Hamburg, declaring war, which i nearly tanked my economy to buy off the Danes.
Yeah, that gave me a reason to aid my comrades.
So anyway, after a long and drawn out war of a few years, hundreds of thousands of florins lost and many thousands of good rhinelanders dead after taking and retaking Arhus (giving it back to denmark every time) in addition to pooling aid packages to my pathetic Danish buddies, I decide "thats it" and cease all assaults at Arhus.
Then... disaster. Venice violates the alliance and besieges bologna, and as General Shepard says in Modern Warfare two, the whole world just f

'n watched. Then they unanimously declared war. In one turn, europe went from lovin the reich to despising it. The next turn, i seek out aid from my dear friends the danes, surely, in my time of need, they would fly to the reichs aid !.... Unitll i found them besieging my forces at Wroclaw.

s.
I have a picture of the venetian betrayal, anyone who plays HRE on VH probably knows it all too well
Also, i resolved that political catastrophe by killing the pope, having my emperor die, and then allying the pope whilst giving him bags of money. Everyone loves money.