Aren't those really easy to explain?

EU opposes the Houthis because they are a horrifying slave state that distributes children as sex slaves to their troops.

EU opposes Russia because it is a horrifying fascist dictatorship that has repeatedly invaded it's neighbors, and constantly talks about it's historical claims to EU territory.

In the NA conflicts it's harder to draw such a clear line, because the conflicts typically have about 15 sides each, but the basic algorithm you can use is generally that EU tries very hard to pick sides based on morality, not geopolitical interests.