Driving off into the sunset together! Buried in the same grave! Were they a romantic couple? Time to do research:

In 1917, he married Gladys Sims, who was on trial for her husband's murder. The husband's brother-in-law, Gus McMeans, ambushed them, and in the ensuing shootout McMeans was killed. There was no investigation.
Frank also stalked and threatened José Tomás Canales, a state representative who was investigating corruption in the Texas Rangers. He was not charged.
And that's just the summary on wikipedia. Quite a piece of work.
Frank was married twice, and had two kids, Billy Beckham Hamer and Francis Augustes Hamer (that's how it's spelled). He died in 1955.

Maney Gault (left, with Frank in 1932) doesn't have a wikipedia article, but I read an article in True West magazine. He was born in 1886, and worked as a dairy farmer before the Depression; then he found a job in a sawmill. Frank was his neighbor in Austin, Texas.
They sat up many nights playing cards and playing bluegrass music and um...such.
Frank got Maney a job with the Texas Rangers, and they started going on cases together. They continued to work together until the Bonnie and Clyde case, whereupon Frank moved on to other jobs. Maney stayed on as a Ranger until his death in 1947, finally supervising a vast territory in west Texas.
He was married, too, to Rebecca Johnson Gault (1886-1955). Two kids, Leona Gault Pannell and Johnson Gullette Gault.
But marriage and children don't preclude same-sex loves. Maybe Frank and Maney had a Brokeback Mountain thing going on. Can you imagine them saying "I won't quit you"?
Ok, I looked up the movie's end credits again. It says "same small tract," not "the same grave."
Find-a-Grave says that they are buried in the Austin Memorial Park Cemetery. They are the ones with crosses: Maney's grave is in the foreground, and Frank's a row back and to the left, about 10 feet away.
Were then 10 feet apart in life, too?
Or closer?