Possessive Pronouns with Gerunds
Use a possessive pronoun with a gerund, the verb form that functions as a noun. This rule is broken frequently, with many writers using the objective case rather than the possessive case.
I didn't like his going ( not him going) to New York without me.
Their smiling ( not Them smiling) irritated her.
Please forgive our intruding. ( not us intruding)