I agree. Evening fussiness is often due to too little sleep during the day. Check with your dp to see when she is napping and if he can maybe push her latest nap a little later in the afternoon so she's not so tired when you get home.
My little guy used to begin his descent into misery every evening at around 5 pm. It drove me nuts because he was so darn tired but it was too early to put him to bed. His last nap was usually 12:30 to 2:30, so it made sense that he was tired, but he just couldn't wait any later to take that noonish nap, so I found a solution that worked for him. I used to lay him down at 5 pm (the instant he started to fuss) and let him fall asleep. Then I'd go and open his door so he'd only sleep 20 minutes or so. That little cat nap usually would cheer him up and he'd be fine until 8 p.m. when he went to bed for the night. Cat naps don't work for all babies, but it got us through those times. Eventually as he got older he didn't need that cat nap anymore which sure made things easier.
