I know from a past experience,  marriage taking place in a DP camp in Germany was then also registered in the local town offices.

You might actually want to search the records that were gathered here:

For which you would learn potentially quite a lot about the people in question.

You could then write to the town administration to ask if they would look for a record of marriage.  Easier for them if you provide as much information as you possibly can.. Names, their birth dates, parents names, and date of marriage or year of marriage.  The more the better.  You most likely will find an email address for the town's administration.   I will guess you can write to them in English, but if you receive no reply in a week to 10 days, write to them in German.

Good luck with your search.

JG