I have been dating this new guy for about 2 months now, and on Friday (Day 4), I wanted to kill him. Not literally, obviously, but every single thing that came out of his mouth was stupid and annoying. Even the way he said my name made me want to scratch my eyeballs out. Just like Artsoul said, EVERYTHING seemed magnified.
Though I live alone, I can totally relate to living with someone who drives you nuts, even though it has NOTHING to do with him.
Make sure to get some time to yourself, even if it's a bath and a book, a walk, or just some time to reconnect. That has really helped me not want to kill the new guy. *WINK*