This question pops up right when my wife asking me about certain toys and where I kept them.
I just answered her: out of sight, out of mind.
That's really gets into her nerves.
But well, it is true that I really forgotten where I had put them.
Though when it comes to love, it will not apply as it will be heart grows fonder as the person is out of sight and the mind will keep things what the person is doing right now.