The worst part of missing someone is not knowing the real reason why he/she left. This is a real torture especially if it happened unexpectedly. You keep asking yourself a never ending why… why it happened all of a sudden when everything seemed to be going just fine.
Letting it go maybe the most sane thing to do but at the back of your mind you still keep on asking why all of sudden you are left alone and why you can’t seem to find the reason behind it. You keep on revisiting the past in the hope of finding a pattern or even a tiny bit of hint but at the end of they day you’re still left with no clue at all and instead of finding what you are looking for, you ended up more confused.
So, maybe you really need to move on and let it go for now. Just hope that one day, you will see the light at the end of the tunnel. One day, you will know why it happened and hopefully appreciate the fact that it happened.