Some suggestions on how a conversation operates in actual life:
When actual people say things, they look for a response. On the other hand, when they hear things, real people don’t always answer.
For example, someone will say something like, “Oh, it’s a beautiful day, today!” and then wait for the other person to return. Ordinarily, the other person says, “Yeah, it’s gorgeous, right?” But sometimes the other person doesn’t say anything at all. They grunt or roll their eyes or stare out of the window.
People learn how to do this as teens, and it’s a beautiful way to show underlying tension.
But, this isn’t fundamentally the end of the conversation, because actual people talk when no one is listening. Even when people don’t reply; real people keep talking a lot anyway.
This behaviour is an exceptional way to show annoyance if your character’s addressing someone, or insecurity if they can’t stand the sound of silence. It can even show some social clumsiness if they can’t pick up on some social signals.
On the opposite side, there are times when someone doesn’t talk at all. Sometimes, real people are too mad or too nervous or too moody or too much of a youngster to speak.
Don’t make your characters talk if they don’t want it!