Shall we let her/him go?

I was reading an impressing weblog. The author explained that his lover who was a very close friend has left him and he thought it was his fault that she has gone. He said about good times they had together, the happiness and laughs and now she's gone. I thought whether he should have let her go or he should asked her to stay? Love is not forceable. We can not force people to love us but sometimes we need to try. May be the other person needs to know the extent of our love. I think he needed to insist her to stay but if she really wanted to go , he should have let her go.