Laurie and Paula are madly in love with each other. Ever since they found each other, their lives have grown more complete by having each other. When Laurie found out that Paula used to be Paul, she didn't care. All that mattered to her was the mind, the heart, soul that she fell in love with. And although Laurie knows that she could save so much trouble from others by not associating with Paula, she would never think to do such a thing. Laurie will be with her soulmate until the end of time.
I think the above is a beautiful scene. The sentiment of true love can warm the coldest of hearts. And yet, it makes me sad. The reason this scene is so beautiful is that it is so rare. All too often, we choose to have the life that is easier for ourselves, even if it harms others. All too often, we shun the one who is different, even if it means we cannot be with the one who completes us.
And I wonder, isn't all beauty tragic? The things that are beautiful are the things that are special. We don't find paper beautiful because we see it every day. Things are beautiful in part because they are rare. And that is sad.
Beauty is a contrast item. It can only exist in a world where most things are not beautiful. The greater the beauty, the less common it is. If we lived in a utopia, nobody would appreciate it.
Since beauty is about juxtaposition, consider the backdrops in your writing. Sadness in the heart of joy; joy in the presence of sadness. Love rebelling against hate. When good fortune occurs in the presence of poor fortune, it's wonderful. When good fortune occurs in the presence of more good fortune, it's very so what. Contrast makes writing interesting. It also makes life poignant.