Here's a tough one, but love and attachment are two different things. I have no doubt that you loved her, but it's the attachment you had for her that is causing your pain. Your mind had assigned her as being a source of happiness for you and when that changed, it hurts.

Love is an emotional state that is concerned with the freedom and happiness of others. The absolute toughest thing to do is to let your love for her speak (instead of your attachment) and wish her to be happy whether or not it is with you.

You did everything you could and did everything right. That's not a blemish on you, but she just wasn't ready for what you could give. You deserve someone that is emotionally mature enough and ready for what you have to offer.