You shouldn't fantasize about your friend's girlfriend.
Matt is a 19 year old with raging hormones who is home alone.
Matt wants to imagine a sexual fantasy.
Matt thinks about a popular social media influencer who is known for her good looks.
Matt thinks about the girl his best friend is dating who he finds quite attractive.
Matt is satisfied indulging in his fantasy about the famous woman.
Matt feels guilty for thinking this way and feels like a bad friend.