Sam Hunt's wife has filed to end their 5-year marriage, citing infidelity as the reason.
Hannah Lee Fowler claims in her legal docs, obtained by TMZ, Sam is "guilty of inappropriate marital conduct," and she goes on ... "guilty of adultery."
The boilerplate code section Hannah cites reads, "The husband is guilty of such cruel and inhuman treatment or conduct toward the spouse as renders cohabitation unsafe or improper."
Sam and Hannah had not announced she was pregnant, but in the docs, she says she's due in May.