"I am marrying today."
That's not a valid sentence, unless the person you are to wed is named "Today". Such is stuff as Abbott and Costello cashed in on.
Of course, taken in context there may be implied antecedents in spoken dialog. Spoken dialog is often incomplete and rife with implied antecedents and frequently does not follow the rules of grammer. Sentence fragments and one-word sentences can about because of that.
Re:The return of pneumatic tubes
by throawayjune on Sunday June 23, 2024 @11:40AM
(#40768247)
It is valid and maybe easier to see with a comma.
“I am marrying, today.”
“Today, I will be marrying.”
It is valid in the context of “i will be engaging in marriage, today (“today, i am entering into a covenant of marriage”)” but it wouldn’t be something that would be heard very often. it’s a more archaic usage.
The problem in your sentence is that the plain form of a verb is used for states, not activities, and marrying is an activity.
"I am marrying today" is just as intransitive, but without the artificially induced grammatical error.