What does it mean to say "good night"

A friend told me that there was once a sincere relationship in her life, with no sparks, no confession and no communication ... She just silently loved someone he thought was worthy of her love, even if the other person had a heart ... She told me that she would miss him once every day before going to bed and then say "good night" to him as a friend ... So, I had a whim. I also have the impulse to say "good night" ... I tried to find the lost relationship with the person I think is most worthy of my love, so I did it ... the first few days didn't feel too difficult. But one day, I held a karaoke party, and one night, I left a "good night" ... fortunately, the other party didn't feel it, so I got used to it in the next few days. I didn't expect the promise of "good night" to be forgotten by me for several days ... until I received his short message: I haven't heard from you for several days ... Maybe this means that we will always be the original ending ... It is not difficult to miss someone, but it is difficult to miss him every day. Not everyone can do it ... only when you really love someone can you not say "good night". Is her "good night" still going on ... She said that after a year, she decided to keep this "good night" in her heart, as long as the person she loved was happy ... Later, I also received a "good night" message and changed to one sender after another ... But I couldn't hold on for more than a month, and the only one missed it and gave up.