I've let a few go in my life. Some harder than others, but as it seems, I'm still waiting for one of them to come back. Maybe they will one day. Just hope they don't all come back at the same time.
What I do know is that I've learned to love people as a whole. Each and every one of them have become special in their own way. Some I've cared for more than others, and some less. Nonetheless, it's the humanity in people that I love the most. I think I've learned to accept that some people aren't meant to be kept and some are meant to be admired from afar. Whatever that may be, we are merely outsiders looking into each others hearts!
So love often, and frequently and don't ever hold back from telling someone you love them. Even if it's a stranger, someone you just met or someone on their way out the door. Moments missed become regrets, and with the less of those the happier you'll be.
Love often and frequently!