My friend gave me this little piece advise, when I told him about an unrequited love: Sometimes all you can do is tell them and hope for the best.
Well what if you were giving the opportunity to tell them countless times, but you never had the courage to because they were with someone else? So you just sit there hating your self and everyone else, watching the one you love be in love with someone else.
What do you do, if you missed you chance to be with them and now you never will. Because their married and they have a kid now.
You can't ask them to get a divorce and run away with you, because they don't believe in it and they'll never leave their child.
So sometimes you can...and sometimes you just can't!