I don't know what to do I feel so sad all the time I have a brilliant boyfriend but keep picking fights with him all the time I feel so low that I don't want to be alive anymore I just feel so alone and empty I just want to feel normal again

Maybe you're not doing enough. Sadness for no reason can be the result of not being mentally and physically active enough.

Flowing water never goes stale.

Did you think about going to see a doctor, or someone to talk to about this? What do you think that you are sad about?

I don't really know what I feel sad about it's like I have a big cloud hanging over me and no mater what I do I can't move it. I just wish I could see the end of the tunnel but every time I think I see it well it gets moved away:(

You must pay a visit to your doctor and explain how you feel. There are so many remedies for this that you do not need to feel this bad. Talk to someone or visit your doctor as soon as you can. If you find it hard to tell them how you feel than write it down. A doctor will understand.