This is wrong right??

Okay so I’ve been trying and trying to get after my boyfriend every time this happens. So when he goes to the restroom his 4 year old niece always follows and he allows her to let him be in the restroom with him while he does his business. Now don’t you think it’s disrespectful and not right? Now to me I know it’s not right and I don’t like it but when I get after him he don’t listen at all he still lets her, I tell him it’s not right it’s just like me going to the bathroom with my brother, it’s gross. I’m sick and tired of it. I mean I understand if they go somewhere like to an event or a store by themselves but when he’s at home with everyone home it’s not approvable.What should I do??