When you open your heart, you open to the abundance of the Universe. For love is the fundamental substance of the Universe and your heart is the doorway through which that substance enters your life. When you judge another you are closing your heart to the love that person brings you. For the Universe is so ordered that every being is designed to bring you love no matter what their behaviour, manner or appearance might suggest.
Since your deepest need and your highest purpose is love, it is built into the fabric of your being that every experience you create or draw to you is designed by you to bring you the love that is your purpose and your hunger. You are your own greatest teacher. Like any good teacher you love to stretch yourself. But as with any good teacher your lessons are not all about tests and trials. You recognise that you grow best when the lessons you give yourself are joyful.
Therefore when you find yourself in a situation where your ability to love unconditionally is challenged, do not see this as a test where you might fail or something that has been imposed upon you from outside. Rather consider the miracle of your heart. Welcome its ability to access infinite love. Recognise that the more open your heart is, the more of this infinite love is yours. And if the difficulty of your current situation makes it hard for you to keep your heart open, then love yourself first of all. Learn the art of unconditional love by loving yourself unconditionally. Understand that every difficult situation you encounter has only come into being to help you to love the part of yourself you have previously excluded from the love you deserve. Every difficult person you meet comes to you expressly from the Source of All to help you open your heart to a part of yourself you are now ready to love.
As you come to love more and more of yourself, more and more of the love that makes up the Universe reveals itself to you. The love you feel for all beings increases, and the distinction between you and them dissolves. You become one with the love of the Universe.