As per the Meta Stack Exchange post How can we get rid of misspelled and unused (or “zombie”) tags? Sally is correct.
I'm a little wary of creating tag synonyms for every single typo that ever happens, even if it's understandable how it might. In this example, it's definitely more work for me to create the tag synonym (and, if Sally hadn't already edited the question, to either edit the question or merge marrage into marriage) than it would be for the typo to simply be fixed and then the tag automatically removed.
Also note that these single-use tags get removed after 6 months.
In this case, I'm going to let it go, but if we suddenly get a deluge of marrage questions - or other similar cases of widely/frequently-misspelled tags - I'm happy to reconsider and do the merge and synonymisation.
It's a misspelling that occurred exactly once, not a trend in incorrect tagging. Just retag that question: you have the editing privilege. The orphaned marrage tag will be automatically deleted at 3:00 UTC, which is less than 12 hours away.
By the way, the same typo appears in the title of that question.