When you want to feel happy, but somehow still get the urge to feel sadness

I feel like I have a somewhat happy life, but a sad soul. But I cant complain. My mother loves me, my father does too. Im with an amaizing boy who makes me happy. These days he is the only one that can make me truly happy. He is amaizing and funny and carring and i just feel like Im terrible. 
Even if my whole day was nice, somehow I still end up feeling alone and miserable. I dont know I think I just needed to get this off my chest. Bye bye!