Life is strange sometimes.
Relationships are truly fragile.
It is possible to be unable to put your finger on how it happened or when it started, but some relationships that have been important to you and have sustained many years, can be gone in an blink without you being about to define when it started to disintegate or articulate how this came about.
It just strikes you all of sudden with total clarity that this person is out of your life and it is unlikely to pick up where you left off. And you know it is time to let go and move on when you realise that you do not feel the tiniest desire to refute and explain your stand. After all, there is really not much point. Worse if you do not feel any regret in moving on.
P.s. Although, I have to admit I am rather taken aback that I am so unemotional about this. At the same time, I am hit by the realisation that it is so easy to let go of some relationships and yet unable to truly let go of others.