Here's the letter of intent we used. I've redacted dates and other info but you get the idea
Statement of Intent to Marry and circumstances of meetings within the immediate two years previous
We, {Petitioner Full name} and {Beneficiary Full name} do state that, we do intend to lawfully marry within, and remain married from, the 90 days after {petitioner} arrives within the United States after receiving a K-1 Visa.
Circumstances of Meetings within the previous 2 years:
{Beneficiary} visited {Petitioner} in 2022, arriving in Los Angeles, California on the {day} of {month}, {year}, and continuing to {Town}, {State} where {Petitioner} and {Beneficiary} met for the first time in person. {Petitioner} and {Beneficiary} resided together in {Town}, {State} until {Petitioner}’s departure back to Australia on the {day} of {month}, 2022 via Los Angeles, California
{Petitioner} visited {Beneficiary} in {City}, {Aus State}, Australia. {Petitioner} arrived in Australia on the {Day} of {Month}, 2022 and departed back to the United States on the {day} of {month}, 2023
{Beneficiary} is currently, as of writing, visiting {Petioner} in {town}, {state}. {Beneficiary} arrived in the United States through Los Angeles, California on the {day} of {month}, 2023 and will be departing on the {day} of {month}, 2023
{Petitioner Full Name} {Beneficiary Full Name}
____________________ ____________________
Date:_______________ Date:_______________