What does it mean to have a red line in fortune telling?

The fortune teller said that the red line between two people has not been broken. What does this mean?

In other words, two people are still predestined friends, but it also depends on the specific analysis of the eight characters.

Telling fortune with fans is a wonderful culture handed down in China for 5,000 years, which is beyond anyone's doubt. Everyone should look at the fortune-telling with a scientific eye. We should not blindly think that fortune-telling by pointing fans is superstition because some poor prophets cheat money and color under the banner of fortune-telling by pointing fans, and we should not foolishly think that fortune-telling by pointing fans is immortal because some prophets who are proficient in five arts and numerology predict accurately. After all, fortune telling is only a technology, and the knowledge of numerology mastered by the forecaster directly affects the accuracy of prediction.