Missing the past

What I saw is just an empty space,
without you nor your shadow stood by.
Whom I listened to is just a different person talking to me,
without the similar way of thinking that I recognized in my mind.
It strikes me so much that everything changes,
I cannot find the same you anymore.
I guess you will never come back.
Maybe I should have just lived in the moment.
I wish I could go back to the past and stop the time.
I wish there will be eternity in those precious moments.
If only I knew that people's heart could change...
Is it only me who stays in the past?
Then, should I bid a goodbye to you or to the past?