and I would just like to know if there is any way to keep it from attacking the birds?
In a word - no. A cat CAN learn to leave birds alone when you are there, but no way will it leave them alone when no one is home. The predatory instinct is just too strong. I would never ever do this.
No, there is nothing wrong with putting the cat in a bedroom when no one is home. This is the only solution, and look at it this way - the cat will be much happier in a cozy bedroom with toys etc. than starving to death on the street.
Maybe your boyfriend could put a little window seat up? Cats love to sit at windows and watch birds, squirrels and just see the world go by!
A nice cat tree to climb and lie on would do very well too!