Hi JayCastor,
I really like where your song is going, and I love the title 'Impossible'... It made me want to check it out. So great start. I'm not an experienced songwriter either, so I'm not sure how helpful my comments will be. I like the idea of an 'impossible' love, and what it tells us about the writer. And I'd like to know a little about why the love's 'impossible', tell me a story, why is it insurmountable?
An idea might be to set up exactly what the song is about in the first two lines - like Adele's 'Someone like you' .....it begins 'I've heard that you've settled down, That you found a girl and you're married now'. So we know right away what the song is about, and then we follow the story all the way through. I think that could work well for your song too.
Overall, I really like the sentiment behind the song, I think you've crafted it well, and it has great potential. Hope these comments are helpful, keep writing and good luck.
Joanne