You have fallen for a close friend, you couldn’t find reasons why. You didn’t intend to, it just happened. You’re aware, he doesn’t feel the same way as you do, he can’t love you back.
Denial has been a form of escape, so you tried, for years; you denied it to yourself as you did to everyone else. But the truth haunts you, your emotions betrayed you, as well as the memories.
It’s bittersweet, seeing him with someone else. Because he had found happiness, not with you, but you can keep him for a lifetime.