The keys to our hearts lie within our own hands.
Although it may feel like it was another that may have unlocked your heart in the past, it was always you. So if you find yourself with your heart all locked up in your current life situation, realize (gently) that you were the one that locked it up, and you will also be the one to set it free. Believing that only another can set your heart free is false, and takes away your own divine right to happiness. This belief places your happiness in a place that is wholly dependent on others. It's up to you, it's your heart, it's your power, you decide how to react to the situations in your life. Allowing outside influences to shut you down really has very little to do with those outside influences, and everything to do with how you are reacting to that which crosses your path. It may not always be easy to stay open, but being the gatekeeper to your own happiness is worth it...because you can leave that gate open!
A broken heart can be very painful, but that breaking doesn't have to shut you down. You can choose to shine as brightly as a supernova as your life goes through massive changes around you. As new galaxy's are formed out of the remnants of that old star, your shining light will be a beacon to call in the most amazing experiences imaginable. You are a complete universe, not just the light of one single star.
There is always a path in the light.