Sadness gives depth. Happiness gives height. Sadness gives roots. Happiness gives branches. Happiness is like a tree going into the sky, and sadness is like the roots going down into the womb of the earth. Both are needed, and the higher a tree goes, the deeper it goes, simultaneously. The bigger the tree, the bigger will be its roots. In fact, it is always in proportion. That's its balance.
What made losing someone you loved bearable was not remembering but forgetting. Forgetting small things first... it's amazing how much you could forget, and everything you forgot made that person less alive inside you until you could finally endure it. After more time passed you could let yourself remember, even want to remember. But even then what you felt those first days could return and remind you the grief was still there, like old barbed wire embedded in a tree's heartwood.