You are not supposed to leave
I hope you understand the pain of changing yourself, for someone, beyond recovery.
And then they leave.
It will just feel like you lost yourself for nothing.
You lost two persons for the want of one.
You change yourself in every way just to complement their life and they will still have the audacity to say
"I didn't ask you to do anything for me".
And you will be left thinking that all of it was your fault just because you expected things.
You will kill yourself thinking that things could have been better.
That is when you will realize how bad it hurts.