Honestly when I found out I couldn't romance Deacon I was so sad fr
Like... he's funny, he vouches for your character when no one else will, he's got a wildly interesting backstory (or does he??), and he's just a really fun companion that I feel would be prime romance material.
That said, I always end up romancing MacCready. He's such a lovely man and it really helps that he's voiced by Matt Mercer x