Changing to someone different from you used to be

So, we had this conversation about my senpai`s plan to go to wedding plan
where his ex will be in the same table.
That person then said, `why don`t you change to be someone that really different from now.`
He answered that he could not but might have to do, then he talked about something I did not understand fully.

But then it came to the point when he said, `I don`t know how to do that. I have never changed myself.` I think I rose my eyebrows that time unconsciously. I wanted to say that he was so fake.
My senpai continued his story then I said,`Maybe some people do that because they think it was so hurtful if they do not change perfectly to somebody else.` I was still in awe about things he said in front of others. Did he said that for real or he just never realized that he has changed and treated some people like he never recognized at all. For example: me? Helloooo!!!
Anyway, I just needed to write it down in order to make it stay out of my head. So I will not think too much about that.