I'm not a kraut (thank God), but I can give a very basic overview of some of the major factors.
1)Germany, more than basically anyone else was hooked on cheap Russian gas, for everything from electricity generation to industry. As a comparison before the war the UK got ~8% of it's gas from Russia, in Germany it was 55%
2)An absolutely fucking retarded failure of foreign policy named Wandel durch Handel (literally change through trade). It's the idea that rather than trying to force regime change through force, or even negative foreign policy like sanctions and shit, you instead increase your trade with assholes in the belief that binding them closer will eventually change them to your viewpoint. Naturally that's a fucking retarded idea and works about as well as you'd expect
3)Somewhat related to 1 and 2 is the fact that Germany's politicians are Russia's bitches. Lefties in the West might moan about alleged Russian interference in the 2016 election, or the Brexit referendum, but that's nothing on their hold in Germany. To wit, former chancellor Gerhard Schroder (the dude who pushed through Nord Stream), is or has been on the board of basically every major Russian oil company, and the consortium that runs the fucking pipeline he insisted on. Or even Merkel herself who insists, despite all the evidence to the contrary, that her foreign policy of basically allowing Russia to do whatever the fuck it wanted in 2014 has absolutely no bearing on the current situation.
4)Because of their collective guilt over muh 6 gorillion the German Armed Forces are a fucking shell of their former selves. Combine that with #2 and the governments have basically neglected them to the point of uselessness, and refuse to do anything to correct it, meaning they can't do much to help Ukraine militarily even if they wanted to.