3 years ago. I met a girl in college. I felt a real connection with here- but I was too scared to ask her out. I still miss her. How can I rectify my mistake?

Use that experience to make more inspired decisions in the future. See how nothing can really prevent you from asking a girl out, something that is completely normal and a beautiful adventure to have. If you can still meet with her, go ahead and make that call, otherwise, go about your life until the opportunity comes, and this is not only about relationships. Most of the times, we contract and then regret of acting in that way. Take it easy on yourself and enjoy whatever comes in knowing that event if you were afraid, that doesn't tell anything about you. You are worthy and you will always be, regardless of the time you take.

Hi there, so sorry that happened to you, I've been there myself with that feeling of missed opportunities, just because I didn't speak up. Please remember that it's never too late. The connection you felt was real, like you said, and your feelings for her are pointing you to the right direction. It doesn't mean something will necessarily come out of this, or that she will still feel connected, or even be available in the way you hope or imagine. However, the only way to know and to reach out to her. You can choose to do so or let it be. But if letting it be no longer satisfies you, and you don't want to deal with the feeling of missing her, then while not trying to reach out? It's natural to feel uncomfortable when we feel vulnerable but at least point, you don't even need to ask her out. Just reach out and find out how she's doing, simply show her you care, and that you are open and available. Good luck! :-)