Leigh Ann Sepelyak, 38, told police she was mad at her boyfriend.
While he was sleeping Sunday, she allegedly poured gasoline on him, lit a match and threw it on him.
She then reportedly grabbed a bucket of urine to put the flames out.
The couple had apparently been using a bucket in place of a bathroom.
The fire burned nearly 25 percent of the man's body. He was taken to the hospital and is expected to survive.