Sister-in-law's husband lived in the city, sister-in-law had not had sex for several days

The sister-in-law wanted to have sex but she was not able to do it because her husband lived in the city to earn, sister-in-law and brother-in-law lived alone in the village. One day when the brother-in-law went out, the sister-in-law started masturbating alone, then the brother-in-law comes and he sees the sister-in-law doing this.