No, no, no! It was all a big misunderstanding and they were really just playing on her Nintendo Switch... er... Swetch... Her brother is just a really passionate player...
*whispers* Please... they offered me money if I used their product in a comment and I need it in order to take the Goddess of Sequels to a fancy bathhouse on her birthday...
"Why do you look at the speck of sawdust in your brother's eye and pay no attention to the plank in your own eye? How can you say to your brother: 'Let me take the speck out of your eye,' when all the time there is a plank in your own eye? You HYPOCRITE, first take the plank out of your own eye, and then you will see clearly to remove the speck from your brother's eye."
- an adaptation of Matthew Chapter 7, verses 3 to 5.
See, it's not always just about "T", "A" and "P" here at FAKKU; once in a while one can learn something serious.
Easier said than done but sooner or later, the tutor-boyfriend will have to tell the brother to mind his own business, and make sure nobody in the house can hear him and his girlfriend fool around - that shows a little courtesy. As for his macho facade of caring for his sister, he should realize she could end up with somebody else far worse.