Somebody that I used to know

Aside, of course, my sensei, he was one of my scientist role model here.
He was very dilligent
No complaints.
He taught student patiently.
And with every strength.
At least, that`s what I knew during one half year working under his training.
I even thought I want to be a scientist with such quality.

Then, he changed.
I don`t know whether it is correlated or not
yet after that person came and became his assistant
and his close friend,
while I became his outer circle
(although he said he never throw me away and all that crap that we are friends)
He never dedicated most of his time thinking about research anymore
He was more into games
He did things just to be done, not because he likes doing it.
Recently, he had new job to teach
He did not even start yet, he already complained about
how difficult it would be
that it was useless
that he will not make it
that he did not want to do it
he was a defeat even before trying to do it
He changed
I am sad for him

He might have reasons

maybe his father`s condition was going down hill
maybe he now has another priority, like having a family
maybe, I will not ever understand
He is a different person to me
The one I knew has died, no longer here
He is a stranger

He is just somebody that I used to know