They have interesting lives.
They are born every second across the world but only the ones born of intensity survive into old age.

Some of them hurt us, prying open invisible skins over hearts to let out boxed up grief.  Some knit up warm cloaks to wrap around you when you're sitting by the window you sat by, an age ago with more than a coffee cup for company. Some stay forever, with details as vivid as the dust motes in a surprise ray of sun leaking in from the curtain crack. Some stay for a while but the colours get muted and while you remember names, your soul knows it not any more. They become bland. Painless, yes, but joyless too.

Some are forced away because they're better than what you are settling for now. They're interesting but they're reminders and those are good only when you are.

And one day, even the ones you want will die and leave an abyss that gazes into the vacuum you will become.
You will forget.
Memories have interesting lives, but their days are numbered too.