It would really be helpful to see a pic so we can see how you can achieve balance in the room.

Yes -- photos of the whole space would be very helpful!

First tip -- paint the door trim and the door itself in the same color as the walls.

Next -- generally -- adding decorative elements like rectanglar artworks on the opposite side would help to add visual balance. Or add a rectanglar "grid" of photos or artworks that would resemble the shape of the doorway.

But the BEST way to add visual balance -- consider adding bookshelves all around the doorway (including over the top) AND on the other side of the fireplace would be the very best idea -- and would create lots of usable storage too! Check around your area and on Craigs List -- there may be local carpenters that could do this job for you ....