Recently, I came across the idea that thoughts may or may not be paired. Meaning, thoughts either lead us to naturally paired other thoughts or a different train of thought completely. Here is an example:

Paired Thought: I have an issue. Next thought: I must fix it.

Random Thought: I have an issue. Next thought: I wonder what song is playing.

Despite knowing that the brain is predictive and not reactive, are thoughts supposed to be paired? In what instances are thoughts unable to be paired?