Both meanings are very close, and I’d say the main difference is the introducing verb : falloir or être. Il faut calls pour, while être does not. (thus your last examples do not work)

être does not call pour and conveys supposition and observation, with an logical inversion, because the observation is the source of the supposition. Supposition: the wolves were brave, observation, they attacked. The logically inversed sentence really means: I see them attack, so I think they are brave.

In the first sentence, on the other hand, no observation is needed. You can say Il faut… pour without actually seeing this happen. It conveys a needed state and the consequence of this state. State: to be in love, consequence: saying this.

Please note that in fact, your question is not related to the emphasizing adverbs sacrément, drôlement, etc. The sentences work without, and the same questions may stem.