When you've come to realized that you've drifted apart from them,
when you start to notice you never say hi to them anymore,
when you've realized they've more fun with others,
when you've noticed they come to your class without the thought of looking for you anymore,
when you felt like the friendship and close bond you used to have is long gone,
you'll blame it on your ignorance.

Why didn't you spend more time with them?
Why didn't you understand them more?
Why...?

What you should have done?
"I... should have... spend more time... with them... shouldn't I?"

Who could you blame?
"Not your friends... yourself"

You should have spent more time with them.
You should have done this, you should have done that.

When you've come to realised all this, it's already too late.

All you can do now is to look at your friends hang out with new ones, regretting, hoping that they'll not end up like you.

But is that going to help?

But there's nothing you can do...

Blame yourself? Too late. Move on.