It's okay to say you need a break. Wedding planning can get very involved and with a full-time job and social life it can take a lot out of you.
So put the wedding books down and stop checking the wedding blogs and plan a weekend getaway with your fiance or make it a girl's weekend if he's starting to get on your nerves -- and no this is not instead of your bachelorette party -- and take the weekend off.
You don't have to buy plane tickets and fly off to an exotic (a/k/a expensive) destination. Hop in the car and book a room at a B&B a few hours away or book a hotel room in the closest big city. Your weekend itinerary can include laying by the pool, spa appointments, shopping, fine dining or sitting in your room reading a (non-wedding planning) book.
Remember that wedding planning should be fun, so if you're not having fun take a break for a few days or a week and come back to it when you're looking forward to attacking the tasks on your to-do list.