When you didn't notice but you just fell inlove with someone you got close to.
But as soon as you notice him, you need to do the right thing and let go since he has already found someone he loves.
Letting go doesn't mean you have to let go of your friendship just over this. Don't just think of your happiness but his, the most important thing is to treasure in what you two have.
And after everything you gone thru, you won't regret even in meeting him. Since you found a valuable friendship with him and together with your friends.