How do I deal with my feelings for my best friend?

My best friend and I have a very close relationship. We've been called soul mates more than once, and spend all our time together. We just get each other. Over the past year, I have come to realize I'm in love with him (actually, not figuratively). I know he's been attracted to me in the past, but he is in a serious relationship now, and is happy in it. As his best friend, I can't imagine trying to get in the middle of anything that makes him happy. I've tried redirecting my feelings for him into doing what I can to help him make his relationship with his girlfriend stronger, and practically, I've managed. Around him, I'm super good relationship advice girl. When we're not hanging out, though, I'm really conflicted. That is, when I'm around him, I am perfectly capable of just being his best friend. When I'm not, the gap between how I feel about him and how I am with him varies between distracting and painful. How do I deal with my feelings on my own without making our friendship uncomfortable? I've tried dating other guys, who have all been amazing and kind and attractive in their own right, but the closeness of my best friend relationship has set the bar almost impossibly high.