I thought this was for one line or a paragraph, not a whole song and we had to explain the meaning.
:shrugs:
My boyfriend has mental health issues which has at one point in our relationship seen him stay at a mental health facility for almost nine weeks.
While he was away I discovered alternative artist Emilie Autumn by accident. Emilie openly has said she suffers from bi-polar.
She penned and sang a song called Swallow which is about her suffering of her mental health problems and to some of her teenage fans whom think it's cool she has this disorder. When I hear this song it makes me wonder if this is what my other half goes through mentally when he goes through his episodes.
A few different lines get to me.
You tell me everything's all right
As though it's something you've been through
You think this torment is romantic
Well it's not, except to you
When I sense that my boyfriend isn't in the right frame of mind, I try to calm him down. By trying for him to focus on positives. He lashes out on me verbally, I know it isn't the real him talking it's the disorder talking.
The brighter the light
The darker the shadow
I don't need a minder
I've made up my mind
Go away
I don't need a minder
I've made up my mind
Go away
I have learnt over the years of when he is at his lowest and it takes over, that he pushes me away when I try to console him.
Finally when I know his mental health problem has taken over these lines gets to me.
But can I trust you?
But I don't want to.
There have been times when he has questioned me with a similar question.
I will swallow
If it will help my sea level go down
I'll take a deep, deep breath
But I'll come back to haunt you if I drown
The last one makes me think that perhaps my other half sees me as his anchor for when he goes into his into his moods and if I don't comply to the changes, he takes it out on me. If I don't follow the changes, he thinks he is losing me.
Hence the "But I'll come back to haunt you if I drown." 
