Someone who comes in your life always make a lasting impact. Even negative impacts helps you make a better person.
I have not forgotten anyone who have ever been part of my life. I miss them and I love them even if I am unable to see them. Life is not a turn on and a turn off button. We are humans and we do get hurt and injured that what makes us so productive.
If someone who left was not right for you may be you were not right for him too. Don't be arrogant in life and thank everyone for being a part of your life. For me a friend lost is my loss more than theirs. We should not lose friends.
Miss people - cry for people and remember people that is beauty of living and don't ever ignore them from your heart and dreams. That is true romance.
Never - you are not a hard drive to erase memories. This comes from our own insecurities where we fail to recognise our weakness and failures. And end up saying ' I don't care ' instead of ' I fucked up.'