What to Do?

What do you do when you love someone in a way that you want to protect them with every ounce of your being, but you know that there is nothing you can do? When they are just out of reach, they're too far gone, or they just won't let you in, what do you do? Pray hard for them. Check. Talk to them until you're blue in the face. Check. Reason with them, cry with them, listen to them, care for them....check, check, check, check. Let them go and trust God to take care of them? What? Really? I know God is in control. I know He loves them more than I do. I know He has a plan that I know not of. But let them go? How do you do that and still be there for them and love them unconditionally? It's like trying to keep a fire going with out a flame. It's like trying to keep a marriage going without love. You can't, can you? Please, if there is a way, tell me how.