It's not that SPD doesn't want a coalition with CDU because they dislike the "GroKo", it's because they want the AfD to be the leaders of the opposition.
The SPD accepted that fate from the very beginning. Going for a 2nd vote might turn the table only if the AfD looses votes and they drop to 4th place. Then SPD and CDU can form the GroKo while the 3rd biggest party becomes leader of the opposition.
All parties are playing 4D chess around the AfD at the moment.
It's not that SPD doesn't want a coalition with CDU because they dislike the "GroKo", it's because they don't want the AfD to be the leaders of the opposition.
That's why CDU/SPD/Grüne will never happen.
The SPD accepted that fate from the very beginning. Going for a 2nd vote might turn the table only if the AfD looses votes and they drop to 4th place. Then SPD and CDU can form the GroKo while the 3rd biggest party becomes leader of the opposition.
All parties are playing 4D chess around the AfD at the moment.