On 28 June 2012 the Bundestag had a voting about a draft law to allow marriage between same-gender couples – and it was declined.
Also see (in German):
http://www.taz.de/Homo-Ehe-scheitert-im-Bundestag/!96406/
http://www.bundestag.de/bundestag/plenum/abstimmung/20120628_3.pdf