great piece of writing! My suggestions...

I stopped envying what I do not have, but feel grateful with what I do have.--> I stopped envying what I do not have, but felt grateful with what I do have.?

 

Upon reading Carpediem’s essay on his marriage taking away his loneliness, --> Upon reading Carpediem’s essay on how his marriage taking away his loneliness?  

I thought I could write something down about --> I thought I could also write something down about?

what my marriage has brought me --> what my own merriage has brought to me?

I no longer mouthing along Annie Lennox’s --> I no longer mouth along Annie Lennox’s (however, not sure on the usage of "mouth along")