Is this kind of situation normal? I'm really confused and a bit traumatized.

So, here's the situation: My brother is in 8th grade and has a male tuition teacher who teaches him four days a week. This same teacher also tutors my neighbor's daughter, who is also in 8th grade (let’s call her B).

Now, the strange part is that B plays badminton with my brother almost every evening, and sometimes she invites me to play too. My mom, my neighbor, and others also play sometime. But I started noticing something unusual: B's mom (my neighbor) regularly invites the tuition teacher to play badminton with her as well. I didn’t think much of it until a few days ago when I saw that when we’re all playing badminton, B's mom and the tuition teacher sneak into B’s house for about 45-60 minutes every day.

Since B and the tuition teacher have the same last name, I assumed they were family. But when I asked B if the teacher was her cousin or uncle, she told me no, he’s just her tutor.

I was really confused and then today when I ask my brother when the tutor would be coming to teach him, and he said around 4:00 PM. However, when I was going to the market at around 4:30 PM, I saw that B and some kids were playing and the tuition teacher was there laughing and talking to B’s mom. This seemed off because he was supposed to be teaching my brother at that time. ( i later found out he shifted the time to 6:30)

I told my mom about it, and she told me with a straight face that the tutor and B’s mom are seeing each other. I was shocked. I couldn’t believe it because B’s mom is married, and I asked my mom about the husband. She told me that the husband knows and is okay with it because he is also with another woman.

I know this might sound unbelievable, but I swear it’s the truth. My question is: Is this kind of thing normal? I’m really confused and a bit traumatized by the whole situation.