How do you stay friends?

What do you do when you have loved and been hurt?
Swore that you would never find another, that you felt that connection with?
Then you find someone that your connected to, and they are connected to you, but one is taken, and is happy?
How do you stay friends?
When you find someone that your starting to complete each others sentences and can stay on the phone for hours, and sit there for 20 min and say nothing?
How do you just stay friends?
If your afraid of losing a person you have fallen in love with,and not planned on it?
So, How do you stay friends, so as not t mess up the good friendship that you have?
I know this may sound weird, and stuff, but you don't find love, Love finds you, so, what do you do, to stay friends?